Reaction control by regulating internal condensation inside a reactor

ABSTRACT

Methods and apparatuses for controlling exothermic reactions involving a first reactant contained in a liquid and a second reactant in a gas to form a reaction product by atomizing the liquid in an environment of a gas and removing heat of reaction by condensing vapors of the liquid in a reaction chamber. Preferably, the condensation takes place on a simultaneously atomized second liquid of lower temperature than the atomized liquid containing the first reactant. The compositions of the two liquids are preferably similar. This invention provides waste minimization and considerable environmental improvement.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of U.S. patent application Ser. No.08/587,967, filed Jan. 17, 1996, now U.S. Pat. No. 5,883,292, where saidapplication is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to methods and devices for making reactionproducts, wherein a first reactant incorporated in an atomized liquidreacts with a gas containing a second reactant, under controlledcondensation and temperature conditions. It provides waste minimizationand considerable environmental improvement.

BACKGROUND OF THE INVENTION

Reactions where a first reactant, dissolved in a liquid, reacts with asecond reactant contained in a gas under increased surface areaconditions are known to the art. Such reactions are carried out indevices as scrubbers, burners, reaction vessels, and the like, forexample.

Atomization of liquids into a gaseous atmosphere is one of the abovementioned techniques described in the art. The atomization techniquesfor conducting reactions, disclosed in the art so far, are rather crudeand lack innovative features for controlling such reactions with respectto: desired reaction product if the reaction product is an intermediate,yield in reaction product, conversion and conversion rate, temperatureprofiles in the reaction zone, average droplet size or diameter,evaporation rates, and the like. Actually in most, if not all, cases,the reaction product is substantially the final product expected underthe crude overall conditions of the reaction. For example, in the caseof a burner, where a fuel is atomized into an atmosphere of anoxygen-containing gas (such as air for example), the final product ofreaction is carbon dioxide, with desired minimization of carbon monoxideand nitrogen oxides as much as possible. In another example, a scrubberfor removing acidic compounds from a gas may use an atomized liquidcontaining alkali or alkaline earth compounds which react with theacidic compounds in the gas to form the corresponding salts. In stillanother example, ammonia and phosphoric acid react under atomizationconditions to form ammonium orthophosphate, which is a final reactionproduct.

On the other hand, reactions which are geared to produce intermediateproducts, especially in the case of oxidations, are not run underatomization conditions, since atomization promotes complete reactions toa final product. For example, oxidation of cyclohexane to adipic acid,or oxidation of p-xylene to terephthalic acid, have not been reported tobe conducted under atomization conditions, and there is no incentive inthe art to do so, since burning of cyclohexane to carbon dioxide hasbeen expected to take place under such conditions. However, theinventors have discovered that in the presence of unexpected intricatecritical controls and requirements of the instant invention,intermediate reaction or oxidation products, such as adipic acid,phthalic acid, isophthalic acid and terephthalic acid, for example, maybe advantageously obtained under atomization conditions.

The following references, among others, describe processes conducted inintermixing liquid with gaseous materials, mostly under increasedsurface area conditions.

U.S. Pat. No. 5,399,750 (Brun et al.) discloses methods for preparingmaleamic acid (aminomaleic acid) by reacting gaseous ammonia with moltenmaleic anhydride under reactant contact conditions of high surface area,for example reacting said gaseous NH₃ with a thin film of said moltenmaleic anhydride or with said molten maleic anhydride in a state ofvigorous agitation.

U.S. Pat. No. 5,396,850 (Connote et al.) discloses a method ofdestroying organic waste in a bath of molten metal and slag contained ina vessel. The method comprises injecting organic waste into the bath toform a primary reaction zone in which the organic waste is thermallycracked and the products of the thermal cracking which are not absorbedinto the bath are released into the space above the surface of the bath.The method further comprises injecting an oxygen-containing gas towardthe surface of the bath to form a secondary reaction zone in the spaceabove the surface of the bath in which the oxidizable materials in theproducts from the primary reaction zone are completely oxidized and theheat released by such oxidation is transferred to the bath. In order tofacilitate efficient heat transfer from the second reaction zone to thebath, the method further comprises injecting an inert or other suitablegas into the bath to cause molten metal and slag to be ejected upwardlyfrom the bath into the secondary reaction zone.

U.S. Pat. No. 5,312,567 (Kozma et al.) discloses a complex mixing systemwith stages consisting of propeller mixers of high diameter ratio, wherethe blades are provided with flow modifying elements, whereby the energyproportions spent on dispersion of the amount of gas injected into thereactor, homogenization of the multi-phase mixtures, suspension of solidparticles, etc. and the properties corresponding to the rheologicalproperties of the gas-liquid mixtures and to the special requirements ofthe processes can be ensured even in extreme cases. Open channelsopposite to the direction of rotation are on the blades of thedispersing stage of the propeller mixers fixed to a common shaft, wherethe channels are interconnected with gas inlet. The angle of incidenceof a certain part of the blades of mixing stages used for homogenizationand suspension is of opposite direction and the length is shorter and/orthe angle of incidence is smaller than those of the other blades. Bafflebars are on the trailing end of the blades on a certain part of thepropeller mixers used similarly for homogenization and suspension,and/or auxiliary blades at an angle of max. 20° to the blade wings arearranged above or below the trailing end of the blades.

U.S. Pat. No. 5,244,603 (Davis) discloses a gas-liquid mixing systemwhich employs an impeller/draft tube assembly submerged in liquid.Hollow eductor tubes affixed to the impeller drive shaft are used toflow gas from an overhead gas space to the liquid in the vicinity of theassembly. The positioning and size of the eductor tubes are such as tomaximize the desired gas-liquid mixing and reaction rate.

U.S. Pat. No. 5,270,019 (Melton et al.) discloses an elongated,generally vertically extending concurrent reactor vessel for theproduction of hypochlorous acid by the mixing and reaction of a liquidalkali metal hydroxide and a gaseous halogen, wherein an atomizer ismounted near the top of the reactor vessel to atomize the liquid alkalimetal hydroxide into droplets in the vessel. The vessel has a sprayingand reaction zone immediately beneath the atomizer and a drying zonebeneath the spraying and reaction zone to produce a gaseous hypochlorousacid and a substantially dry solid salt by-product.

U.S. Pat. No. 5,170,727 (Nielsen) discloses a process and apparatus inwhich supercritical fluids are used as viscosity reduction diluents forliquid fuels or waste materials which are then spray atomized into acombustion chamber. The addition of supercritical fluid to the liquidfuel and/or waste material allows viscous petroleum fractions and otherliquids such as viscous waste materials that are too viscous to beatomized (or to be atomized well) to now be atomized by this inventionby achieving viscosity reduction and allowing the fuel to produce acombustible spray and improved combustion efficiency. Moreover, thepresent invention also allows liquid fuels that have suitableviscosities to be better utilized as a fuel by achieving furtherviscosity reduction that improves atomization still further by reducingdroplet size which enhances evaporation of the fuel from the droplets.

U.S. Pat. No. 5,123,936 (Stone et al.) discloses a process and apparatusfor removing fine particulate matter and vapors from a process exhaustair stream, and particularly those emitted during post-production curingor post-treatment of foamed plastics, such as polyurethane foam, inwhich the exhaust air stream is passed through a transfer duct intowhich is introduced a water spray in the form of a mist of fine dropletsin an amount which exceeds the saturation point; thereafter the exhaustair stream is introduced into a filter chamber having a cross-sectionalarea that is substantially greater than that of the transfer duct, andthe exhaust air stream passes through at least one, and preferably aplurality of high surface area filters, whereby a portion of the wateris removed from the exhaust air stream and collected in the filterchamber prior to the discharge of the exhaust air stream into theenvironment.

U.S. Pat. No. 5,061,453 (Krippl et al.) discloses an apparatus forcontinuously charging a liquid reactant with a gas. The gas is dispersedin the reactant through a hollow stirrer in a gassing tank. The quantityof gas introduced per unit time is kept constant.

U.S. Pat. No. 4,423,018 (Lester, Jr. et al.) discloses a processaccording to which a by-product stream from the production of adipicacid from cyclohexane, containing glutaric acid, succinic acid andadipic acid, is employed as a buffer in lime or limestone flue gasscrubbing for the removal of sulfur dioxide from combustion gases.

U.S. Pat. No. 4,370,304 (Hendriks et al.) discloses methods by whichammonium orthophosphate products are prepared by reacting ammonia andphosphoric acid together at high speed under vigorous mixing conditionsby spraying the reactants through a two-phase, dual coaxialmixer/sprayer and separately controlling the supply and axial outflowrate of the phosphoric acid at 1 to 10 m/sec. and the outflow rate ofammonia at 200 to 1000 m/sec. (N.T.P.). Thorough mixing and a homogenousproduct is obtained by directing the outflow spray into a coaxialcylindrical reaction chamber of a specified size with respect to thediameter of the outermost duct of the sprayer/mixer. The product may begranulated on a moving bed of granules and adjusted in respect of theNH₃ to H₃ PO₄ content by changing the concentration of the phosphoricacid and/or supplying additional ammonia to the granulation bed.

U.S. Pat. No. 4,361,965 (Goumondy et al. discloses a device foratomizing a reaction mixture, said device enabling the reaction mixtureto be atomized in a reactor with the aid of at least a first gas and anatomizing nozzle. This device further comprises a supply of a second hotgas at the top of the atomizing device, serving to dry the atomizedmixture, a supply of a third gas and means for distributing this thirdgas comprising an annular space of adjustable width and adapted todistribute in the reactor said third gas in the form of a ring along theinner wall of the reactor, so as to avoid any contact between thereaction mixture and said wall. The invention is applicable to theatomization of a reaction mixture.

U.S. Pat. No. 4,308,037 (Meissner et al.) discloses methods according towhich high temperature thermal exchange between molten liquid and a gasstream is effected by generating in a confined flow passageway aplurality of droplets of molten liquid and by passing a stream throughthe passageway in heat exchange relationship with the droplets. Thedroplets are recovered and adjusted to a predetermined temperature bymeans of thermal exchange with an external source for recycle. Theprocess provides for removal of undesired solid, liquid or gaseouscomponents.

U.S. Pat. No. 4,065,527 (Graber) discloses an apparatus and a method forhandling a gas and a liquid in a manner to cause a specific interactionbetween them. The gas is placed into circulation to cause it to make aliquid circulate in a vortex fashion to present a liquid curtain. Thegas is then passed through the liquid curtain by angled vanes to causethe interaction between the two fluids, such as the heating of theliquid, scrubbing of the gas, adding a chemical to the liquid and thelike. The vanes are spaced apart and project inwardly from the innerperiphery of an annular support so that the circulating liquid readilymoves into the spaces between the vanes to create the liquid curtain. Anumber of embodiments of the invention are disclosed.

U.S. Pat. No. 4,039,304 (Bechthold et al.) discloses methods accordingto which waste gas is contacted with a solution of a salt from apollutant of the gas. This solution is obtained from another stage ofthe process used for cleaning or purifying the gas. The resultingmixture of gas and solution is subjected to vaporization so as to obtaina dry gaseous substance constituted by the waste gas and the evaporatedsolvent for the salt. The gaseous substance thus formed containscrystals of the salt as well as the pollutant present in the originalwaste gas. The salt crystals and other solid particles are removed fromthe gaseous substance in the form of a dry solids mixture. The gaseoussubstance is subsequently mixed with an absorption fluid such as anammonia solution in order to wash out and redissolve any salt crystalswhich may remain in the gaseous substance and in order to remove thepollutant present in the original waste gas from the gaseous substance.The pollutant and the redissolved salt crystals form a salt solutiontogether with the absorption fluid and it is this salt solution which isbrought into contact with the waste gas. The gaseous substance isexhausted to the atmosphere after being mixed with the absorption fluid.

U.S. Pat. No. 3,928,005 (Laslo) discloses a method and apparatus fortreating gaseous pollutants such as sulfur dioxide in a gas stream whichincludes a wet scrubber wherein a compressed gas is used to atomize thescrubbing liquid and a nozzle and the compressed gas direct the atomizedliquid countercurrent to the flow of gas to be cleaned. The method andapparatus includes pneumatically conveying to the nozzle a material suchas a solid particulate material which reacts with or modifies thepollutant to be removed or altered. The gas used for atomizing thescrubbing liquid is also used as a transport vehicle for the solidparticulate material. In the case of sulfur oxides, the material may bepulverized limestone.

U.S. Pat. No. 3,677,696 (Helsinki et al) discloses a method according towhich, the concentration of circulating sulfuric acid is adjusted to80-98% by weight and used to wash hot gases containing mercury. Thetemperature of the acid is maintained between 70-250° C., and the solidmaterial separating from the circulating wash solution is recovered.

U.S. Pat. No. 3,613,333 (Gardenier) discloses a process and apparatusfor removing contaminants from and pumping a gas stream comprisingindirectly heat exchanging the gas and a liquid, introducing the liquidunder conditions of elevated temperature and pressure in vaporized andatomized form into the gas, mixing same thereby entrapping thecontaminants, and separating clean gas from the atomized liquidcontaining the contaminants.

U.S. Pat. No. 2,980,523 (Dille et al.) discloses a process for theproduction of carbon monoxide and hydrogen from carbonaceous fuels byreaction with oxygen. In one of its more specific aspects it is directedto a method of separating carbonaceous solid entrained in the gaseousproducts of reaction of carbonaceous fuels and oxygen wherein saidproducts are contacted with a limited amount of liquid hydrocarbon andthereafter scrubbed with water, and said carbonaceous solid is decantedfrom said clarified water.

U.S. Pat. No. 2,301,240 (Baumann et al.) discloses an improved processfor removing impurities from acetylene gas which has been prepared bythermal or electrical methods by washing with organic liquids, as forexample oils or tars.

U.S. Pat. No. 2,014,044 (Haswell) discloses an improved method fortreating gas and aims to provide for the conservation of the sensibleheat of such gas.

U.S. Pat. No. 1,121,532 (Newberry) discloses a process of recoveringalkalis from flue-gases.

Currently, oxidation reactions for the production of organic acids,including but not limited to adipic acid, are conducted in a liquidphase reactor with reactant gas sparging. The reactant gas in thesecases is typically air, but may also be oxygen. Sufficient reactant gas,with or without non-reactive diluents (e.g., nitrogen), is sparged--atrelatively high rate--so that the liquid reaction medium is aerated tomaximum capacity (typically 15-25% aeration). The relatively highsparging rates of reactant containing gas feed (hereinafter referred toas "reactant gas"), associated with this conventional approach, haveseveral drawbacks:

Costly reactant gas feed compressors are required to compress makeupreactant gas for sparging. These are expensive to install and operate(high electric or steam consumption), and have many utility problemsresulting in excessive plant downtime.

The required high gas rate makes it extremely difficult to controloxygen content in the reactor at low concentrations (due to the highreactor gas turnover rate).

The required high gas rate makes it extremely difficult to controlreaction temperature at low production rates (i.e., high turndown rate)for a given sized reactor system. This occurs because the gas used forsparging removes energy from the reaction system by volatilizingreaction liquid and liquid solvent--this volatilization effect is quitesignificant at the relatively high temperatures commonly associated withand required for oxidation reactions. Unless carefully balanced by anexothermic heat of reaction, this volatilization will act tosubstantially lower the temperature of the liquid content of thereactor. Thus, a properly sparged system can be designed for goodtemperature control at medium to high production rates, but will suffertemperature loss and loss of temperature control at significant turndownrate.

High reactant gas feed rate results in relatively high reactornon-condensible off-gas rate. Non-condensible off-gases must either betotally purged to atmosphere, or--if oxygen content is high partiallypurged and partially recycled to the reactor. The use of air as areactant gas feed has drawbacks because it results in high rate of purgeto the atmosphere--this is undesirable because this purge must first becleaned in very expensive off-gas cleanup facilities in order to meetever more stringent environmental requirements. The use of oxygen-onlygas feed to the reactor may be undesirable because high spargingrequirements result in low oxygen conversion in the reactor; lowconversion results in high oxygen concentration within the reactor; andhigh oxygen concentration within the reactor may result in excessiveover-oxidation of liquid reactants and liquid solvents with attendanthigh chemical yield loss (i.e., burning these to carbon monoxide andcarbon dioxide). If the oxygen in the reactor is diluted with recyclenitrogen or gaseous-recycle inerts, then both high recompressioninvestment and costs, and recompression utility problems are introduced.

The current technology also suffers from a relatively low ratio ofgas-liquid surface area to liquid reaction mass. The presently availableart does not maximize this ratio. In contrast, the present inventionmaximizes said ratio in order:

to increase reaction rate by increasing the mass transfer rate ofgaseous reactants to liquid reaction sites; and

so as to enable economic operation at relatively low concentration of asecond reactant, such as an oxidant for example, in the gas phase.

Operating at lower oxygen concentration with acceptable conversion ratesin the reactor improves yield by reducing over-oxidations, andeliminates safety (explosion) problems associated with operation in theexplosive oxygen/fuel envelope. In the current technology, reducingoxygen content below traditional levels would result in a non-economicreduction in reaction rate. However, a significant increase in theaforementioned ratio--relative to current levels--would offset this ratereduction thereby enabling economic operation at reduced oxygenconcentration in the reactor.

Another problem with the current technology is the sometimes formationof large agglomerations of insoluble oxidation products in the reactor.These can build up on reactor walls resulting in decreased availablereaction volume, and in unwanted by-product formation due toover-exposure of said accretions to reaction conditions (e.g., hightemperature) in oxygen-starved micro-reactor environments. These canalso form large diameter, heavy solids in the reactor which can resultin damage to expensive reactor agitator shafts and agitator sealsresulting in costly repairs and high utility wear-problems. Finally, thecurrent technology often requires expensive agitation shafts and sealscapable of withstanding corrosive chemical attack and containing highsystem pressures.

Substituting gas-phase reaction systems for liquid-phase reactorsintroduces new problems, chief among which is the difficulty ofidentifying a cost-effective, efficient, non-plugging, long-livedcatalyst system. Liquid-phase catalyst systems are well-developed andwell-understood. Unfortunately, these are non-volatile. Using anon-volatile catalyst in a gas-phase reaction system must necessarilyoften be subject to severe plugging problems as most organic acidsresulting from oxidation reactions are non-volatile solids--unlessdissolved in a liquid reaction medium.

There is a plethora of references dealing with oxidation of organiccompounds to produce acids, such as, for example, adipic acid.

The following references, among the plethora of others, may beconsidered as representative of oxidation processes relative to thepreparation of diacids.

U.S. Pat. No. 5,321,157 (Kollar) discloses a process for the preparationof C₅ -C₈ aliphatic dibasic acids through oxidation of correspondingsaturated cycloaliphatic hydrocarbons by

(1) reacting, at a cycioaliphatic hydrocarbon conversion level ofbetween about 7% and about 30%,

(a) at least one saturated cycloaliphatic hydrocarbon having from 5 to 8ring carbon atoms in the liquid phase and

(b) an excess of oxygen gas or an oxygen containing gas mixture

in the presence of

(c) less than 1.5% moles of a solvent per mole of cycloaliphatichydrocarbon (a), wherein said solvent comprises an organic acidcontaining only primary and/or secondary hydrogen atoms and

(d) at least about 0.002 mole per 1000 grams of reaction mixture of apolyvalent heavy metal catalyst; and

(2) isolating the C₅ -C₈ aliphatic dibasic acid.

U.S. Pat. No. 5,463,119 (Kollar) discloses a process for the preparationof C₅ -C₈ aliphatic dibasic acids, similar to the one described in U.S.Pat. No. 5,321,157, with the main difference that after removing theadipic acid, the remaining matter is recirculated.

U.S. Pat. No. 5,221,800 (Park et al.) discloses a process for themanufacture of adipic acid, according to which cyclohexane is oxidizedin an aliphatic monobasic acid solvent in the presence of a solublecobalt salt wherein water is continuously or intermittently added to thereaction system after the initiation of oxidation of cyclohexane asindicated by a suitable means of detection, and wherein the reaction isconducted at a temperature of about 50° C. to 150° C., at an oxygenpartial pressure of about 50 to about 420 pounds per square inchabsolute.

The following references, among others, describe oxidation processesconducted in multi-stage and multi-plate systems.

U.S. Pat. No. 3,987,100 (Barnette et al.) describes a process ofoxidizing cyclohexane to produce cyclohexanone and cyclohexanol, saidprocess comprising contacting a stream of liquid cyclohexane with oxygenin each of at least three successive oxidation stages by introducinginto each stage a mixture of gases comprising molecular oxygen and aninert gas.

U.S. Pat. No. 3,957,876 (Rapoport et al.) describes a process for thepreparation of cyclohexyl hydroperoxide substantially free of otherperoxides by oxidation of cyclohexane containing a cyclohexane solublecobalt salt in a zoned oxidation process in which an oxygen containinggas is fed to each zone in the oxidation section in an amount in excessof that which will react under the conditions of that zone.

U.S. Pat. No. 3,530,185 (Pugi) describes a process for manufacturingprecursors of adipic acid by oxidation of an oxygen containing inert gaswhich process is conducted in at least three successive oxidation stagesby passing a stream of liquid cyclohexane maintained at a temperature inthe range of 140 to 200° C., and a pressure in the range of 50-350 psigthrough each successive oxidation stage in an amount such thatsubstantially all the oxygen introduced into each stage is consumed inthat stage thereafter causing the residual inert gases to passcountercurrent into the stream of liquid during the passage of thestream through said stages.

None of the above references, or any other references known to theinventors disclose, suggest or imply, singly or in combination, devicesfor conducting reactions under atomization conditions subject to theintricate and critical controls and requirements of the instantinvention as described and claimed.

SUMMARY OF THE INVENTION

As aforementioned, the present invention relates to methods and devicesfor making reaction products, wherein a first reactant incorporated inan atomized liquid reacts with a gas containing a second reactant, undercontrolled condensation and temperature conditions. More particularly,it pertains to a method of making a reaction product in a reaction zonein an exothermic reaction from a first liquid containing a firstreactant and a gas containing a second reactant, the method comprisingthe steps of:

atomizing the first liquid to form a plurality of first droplets in thegas at a first flow rate, at a first atomization temperature, and at areaction pressure;

reacting at least partially the first reactant with the second reactantto form the reaction product and release heat;

evaporating at least part of the first liquid, thereby removing at leasta portion of the released heat; and

restricting the portion of removed heat within predetermined limits bycausing controlled condensation within the reaction zone.

The present invention also pertains to a method of making a reactionproduct in an exothermic reaction from a first liquid containing a firstreactant and a gas containing a second reactant, the method comprisingthe steps of:

dividing the first liquid into a first stream and to a second stream;

causing the first stream to have a first atomization temperature and thesecond stream to have a second atomization temperature lower than thefirst atomization temperature;

atomizing the first stream to form a plurality of first droplets in thegas at a first flow rate and at the first atomization temperature;

atomizing the second stream to form a plurality of second droplets inthe gas at a second flow rate and at the second atomization temperature;

reacting at least partially the first reactant in the first dropletswith the second reactant to form the reaction product and release heat;and

maintaining first droplet temperature within predetermined limits by

evaporation of at least part of the first liquid from the firstdroplets, and

condensation of at least part of the evaporated first liquid on thesecond droplets.

Further, the instant invention is related to a method of making areaction product in an exothermic reaction from a first liquidcontaining a first reactant and a gas containing a second reactant, themethod comprising the steps of:

dividing the first liquid into a first stream and to a second stream;

causing the first stream to have a first atomization temperature and thesecond stream to have a second atomization temperature lower than thefirst atomization temperature;

atomizing the first stream to form a plurality of first droplets in thegas at a first flow rate and at the first atomization temperature;

atomizing the second stream to form a plurality of second droplets inthe gas at a second flow rate and at the second atomization temperature;

reacting at least partially the first reactant in the first dropletswith the second reactant to form the reaction product and release heat;and

maintaining first droplet temperature within predetermined limits bytransferring heat from the first droplets to the second droplets.

The controlled condensation is preferably caused by a second liquidatomized within the reaction zone. The second liquid may containvolatiles at a desired content, the volatiles having a desiredvolatility. The second liquid may enter the reaction zone under acondition selected from a group consisting of a second flow rate, asecond atomization temperature, and a combination thereof, the secondatomization temperature being lower than the first atomizationtemperature.

The first liquid may also contain volatiles at a desired content, thevolatiles having a desired volatility.

The condensation rate may be at least partially controlled by oneparameter selected from a group consisting of (a) temperature differencebetween the first and the second atomization temperature, (b) flow ratedifference between the first and the second flow rate (c) the volatilescontent of the first liquid, (d) the volatiles content of the secondliquid, (e) the volatility of the first or second volatiles, and (e acombination thereof. The condensation rate may also be controlled bychanging the reaction pressure.

It is preferable that, if the first liquid comprises a first set ofingredients, and the second liquid comprises a second set ofingredients, the first set and the second set have at least one commoningredient. It is more preferable that the first set and the second setcomprise substantially the same ingredients, and even more preferablethat the substantially same ingredients are substantially under the sameproportions.

The controlled condensation may be caused by a solid or liquid surfacewithin the reaction zone or by a solid or liquid surface in theperiphery of the reaction zone, or any combination thereof.

Provisions may be made so that condensed material is at least partiallyseparated from reacted material.

It is preferable that the total amount of second reactant fed to thereaction zone is in a range corresponding to stoichiometric to two timesstoichiometric with respect to the total amount of first reactant fed tothe reaction zone.

The present invention also pertains to methods as aforedescribed,wherein

the first reactant comprises a compound selected from a group consistingof cyclohexane, cyclohexanone, cyclohexanol, cyclohexylhydroperoxide,o-xylene, p-xylene, m-xylene, a mixture of at least two of cyclohexane,cyclohexanone, cyclohexanol, and cyclohexylhydroperoxide, and a mixtureof at least two of oxylene, p-xylene, and m-xylene;

the second reactant comprises oxygen; and

the reaction product comprises a compound selected from a groupconsisting of cyclohexanone, cyclohexanol, cyclohexylhydroperoxide,adipic acid, phthalic acid, isophthalic acid, terephthalic acid, amixture of at least two of cyclohexanone, cyclohexanol, and

cyclohexylhydroperoxide, and a mixture of at least two of phthalic acid,isophthalic acid, and terephthalic acid.

The present invention relates also to a method, wherein the first liquidcontains a catalyst at a desired concentration, the first and secondreactants are characterized by desired concentrations, the exothermicreaction is characterized by a conversion of the first reactant toreaction product, the exothermic reaction takes place in a reactionzone, the first droplets have a path within said reaction zone, saidfirst droplets have a temperature as function of their path through thereaction zone, wherein said conversion is controlled by a parameterselected from a group consisting of:

changing the first atomization temperature;

changing the second atomization temperature;

changing the catalyst concentration;

changing the first reactant concentration in the first liquid;

changing the volatiles content in the first liquid;

changing the volatiles content in the second liquid;

changing the second reactant concentration;

changing the droplet size of the first liquid; and

a combination thereof; and

wherein said first droplet temperature is controlled by a parameterselected from a group consisting of:

changing the first atomization temperature;

changing the second atomization temperature;

changing the catalyst concentration;

changing the first reactant concentration;

changing the volatiles content in the first liquid;

changing the volatiles content in the second liquid;

changing the second reactant concentration;

changing the droplet size of the first liquid; and

a combination thereof.

This invention also pertains to a method, wherein the average dropletsize of the second liquid is maintained at least adequately smaller thanthe average droplet size of the first liquid in a manner to decrease theprobabilities of first droplets to collide with second droplets ascompared to such probabilities when the average size of the seconddroplets is substantially the same as the average size of the firstdroplets.

Further, the instant invention pertains to a method, wherein

the reaction product comprises a compound selected from a groupconsisting of adipic acid, phthalic acid, isophthalic acid, andterephthalic acid, and

the method further comprises a step of reacting said reaction productwith a third reactant selected from a group consisting of a polyol, apolyamine, and a polyamide in a manner to form a polymer of a polyester,or a polyamide, or a (polyimide and/or poyamideimide), respectively.

The method may further comprise a step of spinning the polymer intofibers.

The present invention also pertains to an apparatus for making areaction product in an exothermic reaction from a first liquidcontaining a first reactant and a gas containing a second reactant,comprising

a reaction chamber;

a first atomizer in the reaction chamber for atomizing the first liquidat a first flow rate, a first atomization temperature, and at a reactionpressure;

condensing means within the reaction chamber for condensing vapors; and

control means for maintaining first droplet temperature lower than apredetermined value by transferring heat from the first droplets to thecondensing means.

The condensing means may comprise a second atomizer for atomizing asecond liquid at a second flow rate, and at a second atomizationtemperature. It is preferable that at least one of the first and thesecond atomizer is adapted to conduct interrupted atomization at desiredintervals.

The apparatus may further comprise one or more of:

means for measuring the temperature of the droplets within the reactionchamber;

means for recycling the first liquid in the reaction chamber;

a divider for dividing the recycled first liquid into a first stream anda second stream, the first stream being directed to the first atomizerand the second stream being directed to the second atomizer;

heating and/or cooling means (temperature controlling means) forbringing the first stream to the first atomization temperature and thesecond stream to the second atomization temperature;

an arrangement, wherein the control means are adapted to maintain thefirst droplet temperature within predetermined limits by regulating theflow rates and atomization temperatures of the first and the secondliquids;

an arrangement wherein the control means are adapted to utilize dataconcerning temperature profiles in the reaction chamber in order toregulate the flow rates and atomization temperatures of the first andthe second liquids; and

means for feeding a total amount of second reactant in the reactionzone, the total amount of second reactant being in a range correspondingto stoichiometric to two times stoichiometric with respect to a totalamount of first reactant fed to the reaction zone.

BRIEF DESCRIPTION OF THE DRAWING

The reader's understanding of this invention will be enhanced byreference to the following detailed description taken in combinationwith the drawing figures, wherein:

FIG. 1 illustrates schematically a conventional reactor using internalcondensation.

FIG. 2 illustrates schematically another conventional reactor usingexternal condensation.

FIG. 3 illustrates schematically a preferred embodiment of the presentinvention, wherein a first liquid is atomized and condensation takesplace on a solid surface cooled by a jacket around the reaction chamber.

FIG. 4 illustrates schematically still another preferred embodiment ofthe present invention, wherein a first liquid is atomized andcondensation takes place on a solid surface cooled by a coil within thereaction chamber.

FIG. 5 illustrates schematically a highly preferred embodiment of thepresent invention, wherein a first liquid is atomized and condensationtakes place on a liquid surface comprised of droplets of a second liquidhaving a lower temperature than the first liquid and being co-atomizedwith the first liquid.

FIG. 6 illustrates schematically an exemplary control arrangement, whichmay be utilized along with the miscellaneous embodiments of the instantinvention.

FIG. 7 illustrates schematically still another preferred embodiment ofthe present invention, wherein the condensation takes place on a liquidsurface surrounding the reaction zone.

FIG. 8 illustrates schematically still another preferred embodiment ofthe present invention, wherein the condensation takes place on a liquidsurface surrounding the reaction zone, and wherein condensed material isat least partially separated from reacted material.

FIG. 9 illustrates schematically still another preferred embodiment ofthe present invention, wherein the condensation takes place on a solidsurface surrounding the reaction zone, and wherein condensed material isat least partially separated from reacted material.

DETAILED DESCRIPTION OF THE INVENTION

As aforementioned, the present invention relates to methods and devicesfor making reaction products, and preferably intermediate oxidationproducts, wherein a first reactant incorporated in an atomized liquidreacts with a gas containing a second reactant, which may preferably bean oxidant, under controlled conditions. The term "intermediateoxidation product", as aforementioned, signifies that the oxidationstops before substantially oxidizing the first reactant to carbonmonoxide, carbon dioxide, or mixtures thereof. According to the presentinvention, the atomization conditions are subject to intricate criticalcontrols and requirements as described and claimed hereinbelow.

According to the present invention, conversion refers to conversion of areactant to a reaction product. Thus conversion, at any point during areaction, is defined as the percentage ratio of moles of reactionproduct formed during the reaction to the total moles of reactant in thefeedstock, multiplied by the reciprocal of the number of moles ofreaction product produced theoretically when one mole of reactant iscompletely converted to said reaction product.

Transient conversion is the conversion taking place from the point thatthe first liquid is atomized to form first droplets to the point justbefore the first droplets coalesce to a mass of liquid, as describedhereinwith. This occurs in just one cycle of droplet formation anddroplet coalescence.

Reactions which are geared to produce intermediate products, especiallyin the case of oxidations, have not been run under atomizationconditions so far, since atomization promotes complete reactions to afinal product. For example, oxidation of cyclohexane to adipic acid, oroxidation of p-xylene to terephthalic acid, have not been reported to beconducted under atomization conditions, and there is no incentive in theart to do so, since burning of cyclohexane to carbon dioxide has beenexpected to take place under such conditions. However, the inventorshave discovered that in the presence of unexpected intricate criticalcontrols and requirements of the instant invention, intermediatereaction or oxidation products, such as adipic acid, phthalic acid,isophthalic acid and terephthalic acid, for example, may beadvantageously obtained under atomization conditions.

The present invention enables economic oxidation reactions at improvedyield with reduced compression costs and investment, using provencatalyst systems, with reduced off-gas waste-stream discharge to theatmosphere, with reduced off-gas cleanup investment and costs, withoutsolids plugging or buildup problems, with high utility, high conversionrates, and with reduced oxygen concentrations in the reaction chamber.

The ability to operate at lower oxygen concentration, made possible bythis invention, with acceptable conversion rates in the reactor improvesyield by reducing over-oxidations, and may eliminate safety (explosion)problems associated with operation in the explosive oxygen/fuel envelopeby operating in the non-explosive oxygen/fuel envelope. In the currenttechnology, reducing oxygen content below traditional levels wouldresult in a non-economic reduction in reaction rate. In this invention,however, a significant increase in the ratio of gas-liquid interfacialarea to liquid reaction mass--relative to current levels offsets thisrate reduction, thereby enabling economic operation at reduced oxygenconcentration in the reactor.

Yield improvements and/or operation parameters according to thisinvention result in waste minimization and considerable environmentalimprovement, which is a very important for the protection of theenvironment.

Some of the key elements, which may be present singly or in anycombination thereof, in the embodiments of the present invention, are:

High productivity reaction volume;

Elimination of reactor agitator and agitator seals;

Efficient Catalyst Systems;

Low or no off-gas waste-stream rate;

Employment of an ultra-high ratio of gas/liquid interfacial area toliquid reaction volume;

Employment of an ultra-low ratio of liquid reaction volume to liquidvolume contained in the liquid-film diffusion zone attached to the gasinterface;

Variation and accurate control of the ratio of gas/liquid interfacialarea to liquid reaction volume, and the ratio of liquid reaction volumeto liquid volume contained in the liquid-film diffusion zone attached tothe gas interface:

Multi-parameter control of liquid reactant conversion;

Multi-parameter control of liquid reaction mass temperature;

Avoidance of solids buildup in the reactor;

Internal condensation; and

Easy recovery of high purity, high oxygen-concentration off-gas forrecycle with low recompression requirements.

This invention provides a more productive reaction volume than does theconventional technology. Reaction chamber productivity per unit liquidreaction volume is increased due to the greatly enhanced mass transferrates afforded by this invention, coupled, if so desired, with measuresto maximize droplet loading in the reaction chamber. Droplet loading inthe reaction chamber may be maximized according to the presentinvention, by employing internal condensation and generating ultra-smallliquid reaction droplets. The droplet loading, measured as a percent ofreaction chamber volume occupied by the totality of the droplets in thereaction chamber at any one time, is preferably maintained in the rangeof 1-40%. More preferably, droplet loading is maintained in the range of5-30%. More preferably still, droplet loading is maintained in the rangeof 10-20%. Excessively high droplet loading can lead to sudden anduncontrolled coalescence, and is to be avoided. Too low droplet loadingcan lead to low reaction chamber productivity. The optimal control ofdroplet loading and initial droplet size minimizes the coalescence ofdroplets, while in the reaction chamber, optimizes the mass transfer ofoxygen or other oxidant from the gas phase to the liquid phase, andmaximizes the liquid reaction volume available to support the desiredproduct formation.

As it will become clear in the course of this discussion, unlike in theconventional technology which utilizes sparging of oxidizing gasesthrough mechanically agitated liquids containing reactants to beoxidized, there is no reaction chamber agitator and no agitator seals.This process simplification is made possible by the unique reactionenvironment provided by this invention, and is highly desirable as itreduces cost, investment, and improves plant utility compared to theconventional technology.

Since according to the present invention the reaction is conductedwithin the droplets, which are in a liquid phase, the process stillmaintains the advantage of being able to employ efficient liquid-solublecatalyst systems, with the added advantage of attaining reactionconditions almost as efficient as those encountered in a homogeneousgaseous phase. Reactions in a gaseous phase would require costly anduncertain gas-phase catalysts or solid-phase catalyst systems.

Further, this invention enables a low off-gas waste-stream rate, ifdesired, which reduces the off-gas waste-stream rate to the environment,and reduces off-gas cleanup investment and costs, thus resulting inconsiderable environmental improvement. The low off-gas waste-streamrate may be made possible with a near-stoichiometric gaseous oxygen feedcombined with high conversion rates and/or chemical yields, for example.

In the conventional technology, reaction chamber non-condensible off-gasis commonly purged to the atmosphere without partial recycle back to thereaction chamber. This results in increased oxygen consumption andrelated cost, but is done to avoid high, non-economic recompressioncosts and investment. In the conventional technology, recompressioncosts and investment are high due to a high non-condensible load, andhigh recycle pressure requirement:

high non-condensible load results from the relatively high chemicalyield loss, and--in most instances--the use of air as the oxygen source;

high recycle pressure is required to accommodate the high-pressure drop,subsurface sparging (into a liquid-filled reaction chamber) used in theconventional technology;

the high-pressure drop is required, in the case of subsurface sparging,to overcome the liquid head in the reaction chamber and to providehigh-power mixing; and

high-power mixing is necessary, in the case of the conventionaltechnology, to improve gas/liquid contacting and thereby accelerate therate of oxygen transfer into the liquid phase.

When condensation is employed at a stage before the pressure drop(internal condensation), the increased oxygen consumption and relatedcost, and the high, non-economic recompression costs and investmentassociated with the conventional technology are avoided. Internalcondensation according to this invention is condensation ofcondensibles, which takes place within the pressurized system and beforepressure drop to about atmospheric pressure. Inside condensation orinside internal condensation is condensation which takes place withinthe reaction chamber. According to this embodiment, it is possible torecycle oxygen-containing off-gas back to the reaction chamber withrelatively low or no recompression requirement and cost. The recycle maybe even eliminated without incurring significant adverse economicimpact. When condensation is employed at such a stage, the recompressionrequirement is minimal--compared to the conventional technology--due tothe low non-condensible off-gas rate, especially whennear-stoichiometric oxygen feed is used. The low non-condensible off-gasrate is due to the combination of near-stoichiometric oxygen feed, withone or more of high second reactant conversion rate, high chemicalyield, and internal condensation, enabled and provided for by theinstant invention.

According to the instant invention, when near-stoichiometric oxygen feedis desired, it is achievable by the high conversion of the oxygen feedto the reaction chamber per pass, hence needing little recyclerequirement. The high chemical yield results in low non-condensibleby-product formation, thereby significantly reducing off-gas purge loadgenerated in the reaction chamber. Reduced off-gas purge load in turnreduces oxygen purge from the reaction chamber. Reduced oxygen purgefrom the reaction chamber minimizes oxygen recycle requirement. Theimplementation of internal condensation further reduces recompressionrequirement, as internal condensation outside the reactor furtherreduces oxygen recycle required, and the implementation of internalcondensation inside the reactor reduces oxygen recycle requirementfurther still. This internal condensation significantly reduces oxygenphysical yield-loss. In the limit, internal condensation, completeoxygen conversion per pass, i.e., stoichiometric oxygen feed, and zeronon-condensible by-product formation would result in zero oxygenphysical yield loss and zero recompression requirement. Due to the lownon-condensible off-gas rate made possible when internal condensation isemployed, it is significantly less costly (compared to the conventionaltechnology) to forego recycle.

In this invention, solids buildup in the reaction chamber may beprevented by washing the walls of the reaction chamber with preferablycooler, preferably catalyst-free liquid solvent, or with preferablycatalyst-free liquid reactant, or with a mixture thereof. All surfacesof the reaction chamber, or a certain portion of those surfaces prone tosolids buildup, may be washed in this manner. The wash liquid may besprayed onto the surfaces so washed, or may be generated in situ as aresult of internal condensation. Solids buildup is prevented because thesolids in contact with these surfaces are continuously washed out of thereaction chamber. Furthermore, reaction in the wash-liquid is greatlyminimized by the lower temperature or absence of catalyst, the shorthold-up-time or a combination thereof. All solids produced in thereaction chamber are removed from the reaction chamber with the washliquid.

In the embodiments of this invention involving off-gas recycle, thisinvention provides means by which the recompression requirement can begreatly minimized or eliminated. Due to the small non-condensibleoff-gas rate associated with this invention, it is possible to educt therecycle off-gas into the reaction chamber using a liquid stream as themotive force.

In the conventional technology, gas sparging bubbles are dispersed in acontinuous liquid-phase comprised of liquid reactants, liquid solvents,dissolved reaction products and by-products, dissolved gases, anddissolved catalysts. A thin film of liquid is attached and surroundseach bubble, due to strong surface tension forces. While the thicknessof the liquid-film is a function of many variables including, but notlimited to, temperature and viscosity of the liquid solvent and liquidreactant, generally the thickness of the liquid-film is in the range of0.05 inches to 0.0001 inches, and mostly in the range of 0.02 inches to0.001 inches. Reactions can occur in this liquid-film and in thecontinuous-phase liquid surrounding this film. Reaction products may infact be preferentially produced in the film, relative to the surroundingliquid, depending on the nature of the diffusional resistance inhibitingthe transfer of materials from the liquid film into the surroundingliquid. In any event, it is expected that a significant amount ofreaction will occur in the liquid-film due to its immediate proximity tothe gas-phase second reactant, such as oxygen or other oxidant forexample. In the conventional technology, the ratio of liquid reactionvolume to liquid volume in the liquid-film is extremely high--typically,this would be several orders of magnitude. This extremely high ratioleads to two highly undesirable consequences:

First, it leads to gross non-homogeneities in the concentration ofreaction products between the two zones, with high localized productconcentrations building up in the liquid-film. These high localizedconcentrations arise in the liquid-film in the conventional technologybecause a significant (perhaps even predominant) amount of reactionoccurs in the liquid-film due to its immediate proximity to thegas-phase reactant, and because reaction products so formed in theliquid-film must necessarily increase in concentration--relative to thesurrounding bulk liquid--to overcome diffusional resistance and migratefrom the liquid-film out into the surrounding liquid. Furthermore, for agiven production rate and conversion, the higher the ratio the higherthe product concentration in the liquid-film. The worst consequence ofhigh localized product concentration in the liquid-film in theconventional technology is that it leads directly to over-reactionproducts, such as over-oxidation for example. Over-oxidation resultswhen already formed product continues to be exposed to reactive forms ofoxygen. Over-oxidation in turn causes chemical yield loss, high productpurification costs, and high waste disposal costs.

Second, it leads to poor utilization of the total available reactionvolume. This results because the most productive reaction volume is thatin closest proximity to the gas-phase oxygen. The reaction volumeclosest to the gas-phase oxygen is the liquid-film. At very high ratiosthe amount of volume occupied by the liquid-film is extremely small;hence, the poor utilization at high reaction volume.

This invention overcomes the aforementioned problems associated with theconventional technology by converting the reaction system to ultra-lowratio of liquid reaction volume to liquid volume in the liquid-film.This is the exact opposite of the conventional technology. In thisinvention, ultra-low ratios are obtained by converting the bulk stirredliquid phase to spray droplets of controlled small size suspended in thecontinuous gas-phase. The size of the droplets may be controlled suchthat the average radius of the droplet is preferably less than about 10times the thickness of the diffusion film associated with theconventional technology. More preferably, the droplets should becontrolled such that the average radius of the droplet is on less thanabout 5 times the thickness of the diffusion film associated with theconventional technology. More preferably still, the droplets are to becontrolled such that the average radius of the droplet is less thanabout 1 time the thickness of the diffusion film associated with theconventional technology. In this way, the ratio can be decreased byorders of magnitude below that possible in the conventional technology.This is highly desirable because it enables a significant reduction inover-reaction with concomitant reduction in impurity levels, reductionin purification costs and investment, and reduction in waste-streamload, without loss of production rate, and with more efficientutilization of liquid reaction volume in the reaction chamber (comparedto the conventional technology).

Further, in the conventional technology, the ability to generate a highratio of gas/liquid interfacial area to liquid reaction volume isconstrained by natural effects (including liquid surface tension) tocertain practical maximums. Heroic efforts, including high gas spargingrates and powerful agitation systems, have been employed to achieveoperation near the upper maximum limit. The inventors theorized that amuch higher ratio would be desirable, since it would facilitate thediffusion of oxygen reactant into a liquid film surrounding each gasbubble. This film is strongly attached to the bubble by strong surfacetension forces. Reaction can occur in this film and in thecontinuous-phase liquid surrounding this film, and the ability to effectreaction in either zone is dependent on oxygen diffusion from thegas-phase into the film. In the conventional technology, higherdiffusion rates may be only achieved by either increasing oxygen orother oxidant concentration in the gas passing through the liquidreaction phase, or by increasing the gas sparging rate. However, this isof very limited value, and only small improvements in diffusion ratesmay be made.

In contrast, according to this invention, huge improvements in diffusionrates may be made by using ultra-high ratios of gas/liquid interfacialarea to liquid reaction volume, which are obtained by converting thebulk stirred liquid phase into spray droplets of controlled small sizewithin a continuous gas-phase. For this purpose also., the size of thedroplets should be controlled such that the radius of the droplet is onaverage preferably less than about 10 times the thickness of thediffusion film associated with the conventional technology. Morepreferably, the droplets should be controlled such that the radius ofthe droplet is on average less than about 5 times the thickness of thediffusion film associated with the conventional technology. Morepreferably still, the droplets are to be controlled such that the radiusof the droplet is on average less than 1 time the thickness of thediffusion film. By this method, the ratio of gas/liquid interfacial areato liquid reaction volume can be increased by orders of magnitude abovethat possible in the conventional technology. This is highly desirablebecause it enables a significant reduction in the oxygen concentrationin the gas-phase without loss of production rate (compared to theconventional technology), or, alternately, higher oxygen diffusion rates(hence higher production rates) at comparable oxygen concentration inthe gas-phase.

The significant reduction in the oxygen concentration in the gas-phase,concurrent with still maintaining desirable high reaction rates, madepossible by this invention, is extremely desirable because it acts toimprove yield by reducing over-oxidation, improve safety by enablingoperation further away from the oxygen/fuel explosive envelope, andminimize the amount of oxygen swept from the reaction chamber.Minimizing the amount of oxygen swept from the reaction chamber withother non-condensibles is desirable because it significantly reduces:(1) costly investment for waste off-gas environmental cleanupfacilities, (2) waste off-gas discharges to the environment, thusproviding considerable environmental improvement, and (3) veryexpensive, high maintenance, and potentially unsafe recompressionrequirements (all three of which cause problems in the conventionaltechnology).

According to the present invention, variation and accurate control ofthe ratio of gas/liquid interfacial area to liquid reaction volume, andthe ratio of liquid reaction volume to liquid volume contained in theliquid-film at the gas interface are provided. Since, in the presentinvention, the gas-phase is the continuous-phase, both ratios may besimultaneously controlled by controlling the average droplet size andthe droplet size distribution spectrum. For small droplets, surfacetension forces will pull the droplets into near spheres. For sphericaldroplets, the ratio of gas/liquid interfacial area to liquid reactionvolume is inversely proportional to droplet diameter, and the ratio ofliquid reaction volume to liquid volume contained in the liquid-film isdirectly proportional to droplet diameter. Consequently, ultra-highratio of gas/liquid interfacial area to liquid reaction volume andultra-low ratio of liquid reaction volume to liquid volume contained inthe liquid-film can be simultaneously achieved and controlled byreducing droplet diameter to very small, controlled diameters.Specifically, as aforementioned, the size of the droplets is to becontrolled such that the diameter of the droplet is on average less than10 times the thickness of the liquid-film associated with theconventional technology. However, since droplets of increasingly smallsize contain diminimous reaction volume, and since little furtheradvantage is to be gained in enhanced reaction rate and reducedover-reaction, preferably the droplets are to be controlled such thatthe diameter of the droplet is more than 0.5 times the thickness of theliquid-film associated with the conventional technology. More preferablythe droplets are to be controlled such that the diameter of the dropletis more than 1 time the thickness of the liquid-film associated with theconventional technology. While the thickness of the liquid-filmassociated with the conventional technology is a function of manyvariables including, but not limited to, temperature and viscosity ofthe liquid solvent and liquid reactant, generally the thickness of theliquid-film is in the range of 0.05 inches to 0.0001 inch. In absoluteterms the preferred average droplet diameter is in the range of 0.001 to0.2 inch.

The ways to control average droplet diameters in atomization iswell-known to the art, and it includes, but is not limited to, nozzledesign, variable nozzle characteristics, pressure of atomized material,pressure of gas if gas is used for the atomization process, and thelike.

The control of conversion within tight ranges and at desired levels iscritical to a well run process. Erratic control leads to poor chemicaland physical yields, process upsets, high purification costs, high traceimpurity levels, high recycle requirements, lost utility, and reducedplant capacity. Too low conversion results in high recycle requirements,reduced physical yield, higher unit plant investment, higher unit energyconsumption, and reduced plant capacity. Too high conversion leads toover-reaction, poor chemical yields, high purification costs, high traceimpurity levels, higher unit plant investment, and reduced plantcapacity. In this invention, multiple ways are provided to controlconversion. Conversion may be controlled at a desired level bymanipulation of variables, either alone or in combination with eachother. Some of these variables are:

Oxygen concentration in the reaction chamber.

The ratio of the concentrations of liquid solvent to liquid reactant inthe liquid feed to the reaction chamber.

The concentration of catalyst in the liquid feed to the reactionchamber.

The hold-up time of the liquid feed in the reaction chamber.

The size or diameter of the droplets in the reaction chamber.

The temperature of the droplets.

According to this invention, conversion can be controlled, for example,by regulating the oxygen concentration in the reaction chamber. This isto be done by using oxygen as the limiting reagent. In this instance,the rate of oxygen feed to the reaction chamber would be increased ordecreased as required to control conversion. Conversion isincreased--holding all other parameters constant--by increasing oxygenfeed rate, and thereby increasing oxygen concentration in the reactionchamber. Conversion is decreased--holding all other parametersconstant--by decreasing oxygen feed rate, and thereby decreasing oxygenconcentration in the reaction chamber.

Further, conversion is increased--holding all other parametersconstant--by increasing the concentration of catalyst in the liquid feedto the reaction chamber. Conversion is decreased--holding all otherparameters constant--by decreasing the concentration of catalyst in theliquid feed to the reaction chamber.

In addition, conversion is increased--holding all other parametersconstant--by increasing the hold-up time of the liquid feed in thereaction chamber. Conversion is decreased -holding all other parametersconstant--by decreasing the hold-up time of the liquid feed in thereaction chamber. Hold-up time of the liquid feed in the reactionchamber is controlled by varying the height of the gas-phase through thedroplets fall. Hold-up time is increased by increasing the height, anddecreased by decreasing the height. The height may be controlled inseveral ways. For example, it may be controlled by:

Raising or lowering the height of the droplet spray nozzle or nozzles.

Raising or lowering the height of a liquid pool at the liquid level atthe end of the vertical reaction chamber. The height of the liquid poolcan be determined and controlled by a variety of ways well known to theart.

Also, conversion is increased--holding all other parameters constant--bydecreasing the size of the liquid droplets in the reaction chamber.Conversion is decreased--holding all other parameters constant--byincreasing the size of the liquid droplets in the reaction chamber.Droplet size inversely affects conversion by controlling oxygen masstransfer into the liquid reaction media. Since the ratio of surface areato volume for a spherical droplet is inversely proportional to thediameter of a droplet, and since oxygen transport from the gas-phase isdirectly proportional to the surface area of a droplet, then the ratioof oxygen mass transport to the liquid volume contained in a dropletvaries inversely with the diameter of the droplet. Therefore, therelative oxygen mass transfer for larger droplets is smaller than thatfor smaller droplets, and conversion is correspondingly reduced when allother parameters are held constant.

Because reaction rates are faster at higher temperatures, in thisinvention, conversion is increased--holding all other parametersconstant--by increasing the temperature of the liquid droplets.Conversion is decreased--holding all other parameters constant--bydecreasing the temperature of the liquid droplets in the reactionchamber.

According to this invention, the heat of reaction may be removed fromthe liquid reaction mass as vaporized liquid reactant and vaporizedliquid solvent. These vaporized materials may be condensed eitheroutside or inside the reaction chamber as it will be discussedhereinbelow. Removal of heat inside the reaction chamber may beconducted for example by using condensation sprays, or condensationsurfaces, or a combination thereof.

It should be stressed that internal condensation may take place eitheroutside or inside the reaction chamber, as illustrated later. Internalcondensation is condensation which takes place within the system, beforethe pressure is relieved. Internal or external (outside the pressurizedsystem) should not be confused with inside (inside the reaction chamber)and outside (outside the reaction chamber) conversion.

In the case of condensation sprays, a portion of recycled liquid may becooled in a heat exchanger or brought to a desired temperature by othertemperature control means well known to the art, external to thereaction chamber, and be sprayed onto the interior reaction chamberwalls, or into the gas-phase of the reaction chamber, or both. In thecase where said spray is directed onto the reaction chamber wall, and inthe instance where reaction products are relatively insoluble in saidspray, then streams after filtering out the reaction products arepreferable. The absence of catalyst in this case is also important,because this absence and the relatively cold nature of the incomingstreams act to prevent reaction in said spray on the interior wall ofthe reaction chamber. In the case where reaction products are relativelyinsoluble, this absence of reaction prevents the highly undesirableaccumulation of solids on this surface. Condensation spray is effectivebecause hot, condensible gases inside the reaction chamber condense onthe cool, liquid surface. The amount of condensation induced in thismanner may be controlled by regulating the flow rate, temperature, andposition of the condensation spray. Increasing the flow rate, decreasingthe temperature, and controlling the condensation spray so as toincrease its liquid surface area act individually or in combination toincrease the rate of condensation of the vaporized liquid containing thereactant and vaporized liquid solvent; the converse is also true.

Furthermore, in the case of condensation sprays, this invention providesboth the means to control the liquid surface area of the condensationspray, and the means to prevent excessive contact of the reaction liquidspray with the condensation spray. Where condensation spray is directedagainst the side of the reaction chamber wall, the condensation surfacearea may be effectively controlled by manipulating the impingementposition of the condensation spray nozzles on the side of the reactionchamber wall. Directing this spray higher up the side of the reactionchamber wall increases the condensation surface area. Conversely,directing it lower decreases the condensation area. Where thecondensation spray is directed into the gas-phase of the reactionchamber, the condensation surface area may be effectively controlled bymanipulating the size and amount of the droplets. Since the ratio ofsurface area to volume for a spherical droplet is inversely proportionalto the diameter of a droplet, and since the cumulative volume of all ofthe droplets sprayed into the reaction chamber is fixed for a given flowrate, then the surface area may be easily and precisely increased--whenall other parameters are held constant--by decreasing the droplet size.The converse is also true. Droplet size can be easily controlled usingtechniques well known to the art.

Furthermore, in the case of condensation sprays, it is critical toprevent excessive contact of the reaction liquid spray with thecondensation spray. This is true because the condensation spray may notcontain catalyst and is deliberately cooled well below the reactiontemperature of the liquid reaction media. Excessive mixing of these twosprays could result in a significant reduction in condensationefficiency, reaction rate, or both. Excessive mixing may be prevented inthe first instance by positioning the spray nozzles so as to direct thecondensation spray against the reaction chamber wall, and the liquidreaction spray into the gas-phase of the reaction chamber in a mannerwhich minimizes wall contact. In the second instance, excessive mixingmay be prevented by selecting a spray nozzle for the condensation spraywhich produces a very small diameter droplet. This technique iseffective because very small droplets do not readily mix with similar,smaller, or larger sized droplets, thereby preventing the undesiredcontact with the liquid reaction spray. Furthermore, producing a verysmall condensation spray droplet is highly efficient, from thestandpoint of the desired condensation of vaporized liquid reactant andvaporized liquid solvent, because it increases the condensation surfacearea.

In the case of condensation sprays, and in the second instance, wherethe condensation spray is directed into the gas phase of the reactionchamber and where excessive mixing is prevented by selecting a spraynozzle for the condensation spray which produces a very small diameterdroplet, this invention provides a reaction system in which the liquidcontents of the reaction chamber are comprised of two different droplettypes: both types simultaneously occupy the same reaction environmentand each is in close proximity to the other, but each type remainsseparate, each may contain different concentrations of liquid solventand liquid reaction chemicals, each type may be at significantlydifferent temperatures, and each may perform different functions(namely, either condensation or reaction).

In the case where vaporized liquid reactant and vaporized liquid arecondensed inside the reaction chamber on metal surfaces, this may beaccomplished in the first instance by externally cooling the reactionchamber walls with an external cooling jacket through which iscirculated a cooling medium, like cooling water; or, in the secondinstance, by providing a cooling coil or other cooling surface insidethe reaction chamber through which is circulated a cooling medium, likecooling water. In the first instance, condensation occurs inside thereaction chamber when condensible gases come into contact with theexternally cooled reaction chamber walls. The walls cooled by thismethod may be the vertical sides of the reaction chamber, or the top, orthe bottom, or a combination thereof. In the second instance,condensation occurs when the condensible gases come into contact withthe internal cooling coils or other cooling surfaces inside the reactionchamber.

According to this invention, non-condensible gases are swept away fromthe condensation surfaces (regardless of whether these condensationsurfaces are the ones produced by the use of condensation sprays or bysolid surfaces) by gaseous eddie currents inside the reaction chamber.These eddie currents may be induced by the combined liquid sprays insidethe reaction chamber. The efficient removal of the non-condensible gasesfrom the condensation surfaces is critical, because unless this is done,the condensation surfaces become blanketed by the non-condensibles, andthe desired condensation is greatly diminished.

As already discussed, according to this invention, non-condensiblereaction by-product gases may be purged from the reaction chamberthrough an overhead gas outlet or they may be purged out the bottom ofthe reaction chamber. In the former case, the small diameter liquidreaction droplets, or the small diameter liquid reaction droplets alongwith very small condensation spray droplets, produced according to themethods of this invention, fall to the bottom of the reaction chamber,where they coalesce and exit the reaction chamber. In the latter case,the small diameter liquid reaction droplets, or the small diameterliquid reaction droplets along with the very small condensation spraydroplets, either fall to the bottom of the reaction chamber and coalescethere, or are swept by the non-condensible purge gases into a swirlingvortex at the bottom of the reaction chamber and, thereby, are broughtinto extremely close proximity with the liquid, where they coalesce, asit will be discussed in more detail later. The extremely close contactso induced is sufficient to coalesce the small diameter liquid reactiondroplets, or the small diameter liquid reaction droplets along with thevery small condensation droplets, from the gas purge into the liquidphase. In both cases, therefore, the liquids exiting the bottom of thereaction chamber may remove both the reaction liquid spray, and thecondensation spray, if present, from the reaction chamber.

Control of droplet impingement (to each other) resulting in increase ofdroplet size is very important, and as mentioned above, it may becontrolled by controlling the droplet size of the first liquid or thesecond liquid or both. Reduction of the droplet size and decrease of thereactor loading favor the avoidance of impingement. Loading of thereactor is defined as the total volume of liquid divided by the totalvolume of the reactor.

Monitoring carbon monoxide and carbon dioxide in the off-gases is aprudent precaution, since unexpected or higher than normal amounts ofcarbon monoxide and/or carbon dioxide signify poorly controlled oruncontrolled oxidation. Similar overriding rules applied by thecontroller help in preventing poor yields, conversions, and evenexplosions.

In addition, carbon monoxide is harmful to the atmosphere and thereaction should be driven in a way to avoid its formation as much aspossible. Optimization of the reaction conditions according to theinstant invention has a beneficial effect in this respect.

Our patent applications Ser. Nos. 08/477,234, 08/478,257, 08/477,195,and 08/475,340, all of which were filed on Jun. 7, 1995, and all ofwhich are incorporated herein by reference, disclose and claimmiscellaneous methods and apparatuses for controlling reactions ingeneral with special emphasis to oxidations, which may be combined withthe embodiments of the present invention in any suitable manner, thusincreasing even further waste minimization and resulting in considerableenvironmental improvement.

Referring now to FIG. 1, there is depicted a conventional reactor 10,comprising a reaction chamber 11, connected to a condenser 12, which inturn is connected to a valve 13. A gas line 14 is also provided close tothe bottom of the reaction chamber 11 for bubbling gas through a liquidcontaining a reactant, which reactant reacts with the gas a component ofthe gas to form a reaction product. The reaction chamber 11 may bepressurized, especially when the temperature required for the reactionto take place is higher than the boiling point of the liquid. Thissituation is very often encountered in the case of reactions involvingorganic compounds. Examples include, but are not limited to formation ofcyclohexanone or cyclohexanol, or cyclohexylhydroperoxide, or adipicacid from cyclohexane by oxidation of the latter, usually by oxygen.Similar examples include formation of phthalic, isophthalic, orterephthalic acid by oxidation of the corresponding xylenes.

This type of condensation may be labeled as internal outsidecondensation, since it takes place within the pressurized zone(internal), but outside the reaction chamber (outside).

In this conventional case, large amounts of gases have to pass throughthe liquid in the form of gas in order to achieve an appreciable degreeof reaction. This may not be true in the case of salt formation, wherefor example, an acidic gas passes through an alkaline liquid. However itis true for most organic reactions of this sort, and especiallycontrolled oxidations (leading to intermediate oxidation products, otherthan carbon monoxide and/or carbon dioxide), wherein special attentionhas to be paid for avoiding combustion, or even explosion. The amount ofgases increases even further if the gaseous reactant, such as oxygen forexample, is diluted with an inert gas, such as nitrogen for example. Inorder to keep the gaseous flow adequately high for the reaction, andmaintain the pressure within acceptable limits, valve 13 has to be openenough to allow the voluminous unreacted gases to escape to theenvironment. Recirculation of the high volumes of gases into the systemis difficult and uneconomical.

The main purpose of the condenser 12 in this conventional case of FIG.1, is to remove condensibles from the voluminous gases before theyescape to the environment. However, no matter how efficient thecondenser 12 is, a small amount of condensibles will escape throughvalve 13 along with the gases. In reactors, such as the one illustratedin FIG. 1, removal of heat could be accomplished by direct cooling ofthe liquid, since the temperature of the liquid is actually thetemperature which has to be controlled. Direct cooling of the liquid maybe done, for example, with a jacket around the liquid or by a coilwithin the liquid. The gas/liquid interface, however, is too small inmost cases for efficient cooling. In most cases the heat is removed by avolatile solvent in the liquid which evaporates during the course of thereaction. In the case of highly exothermic reactions, the massiveamounts of evaporated solvent force large amounts of the gaseousreactant, such as oxygen for example, to follow the same path andfinally be removed through valve 13. Recirculation of the gaseousreactant is very expensive, since it requires efficient high pressurecompressors.

In the reactor of FIG. 1, even if one had the valve 13 substantiallyclosed, and were feeding just enough gaseous reactant, such as oxygenfor example, to maintain a desired pressure by replacing the reactedamount of gaseous reactant with the liquid, comprising cyclohexane forexample, the condenser would be filled with non-condensible gases at anearly point, and condensation of condensibles would be reduceddrastically if not ceased altogether.

An internal (within the pressurized system) inside (within the reactionchamber) condenser (not shown) would not serve much of a purpose, sincethe liquid/gas interface is too small, and removal of reaction heat bycondensation as a primary means heat removal would not be practical inthis conventional arrangement.

Another conventional arrangement is illustrated in FIG. 2, wherein thecondenser 12 is located after the valve 13, and outside the pressurizedzone. In this case an additional condensate tank 16 to collect thecondensed condensibles, which may be recycled into the system. Theproblems described in the previous case become even more acute in thisarrangement, especially with respect to increased contamination of theoff-gases.

In contrast to the above conventional systems, internal insidecondensation may be used very efficiently according to the presentinvention. Three exemplary arrangements are shown in FIGS. 3, 4, and 5.

In one embodiment of this invention, the reactor comprises a reactionchamber 22 as better illustrated in FIG. 3. The walls of reactor 22 aresurrounded by a condenser in the form of a jacket 24. In the case thatcondensation is desired, a liquid 26, having a suitably low temperature,may be circulated in the jacket 24. The jacket 24 may also be used toheat-up the walls of the reaction chamber 22, by steam for example, ifso desired.

A first atomizer 28 having a plurality of nozzles 30 is disposed withinthe reactor, preferably at the upper end 32.

The reaction chamber 22 is also provided with a gas line adapted todistribute a gas within the reaction zone 34 through a plurality oforifices 36. A gas exit port 38 is preferably located at the vicinity ofthe upper end 32 of the reaction chamber 22, and it is connected tovalve 39. Further, a liquid exit port is preferably located in thevicinity of the lower end 42 of the reaction chamber 22.

The reaction chamber 22 is preferably adapted to withstand suchtemperatures and pressures, which are appropriate for the reactionconditions in the reaction chamber 22, and be suitable for the reactantsand reaction products. Such materials and construction characteristicsare well known to the art. For example, depending on the particularreaction, carbon steel, stainless steel, or Hastalloy may be required.In addition, the inside surface may be protected by coatings or liningsof vitreous or other materials, such as glass or titanium, respectivelyfor example.

The atomizer 28 is preferably of the airless type (does not need anatomizing gas for its operation). Airless atomizers are well known tothe art. The atomizer 28 may be steady at a certain position of thereaction chamber 22, or it may be movable, preferably in an up/downmode.

In operation of this embodiment, a first liquid, for example a mixtureof cyclohexane, a solvent such as acetic acid for example, a catalyst,such as a cobalt salt for example, an initiator, such as cyclohexanoneor acetaldehyde for example, and other desirable adjuncts, inproportions is which may be similar to the ones described in the art forconventional systems, and at an atomization temperature, enters thereaction chamber through the first atomizer 28 and nozzles 30 in theform of atomized or sprayed first droplets. The first liquid comprises afirst reactant, which is cyclohexane in this example. At the same timethat this atomization is taking place, a gas containing a secondreactant, such as oxygen for example enters the system though gas line33 and the plurality of orifices 36 and moves in a substantiallyopposite direction than the first droplets. As the first dropletsproceed within the reaction zone 34 from the upper part 32 toward thelower part 42 of the reaction chamber 22, the second reactant, oxygenfor example, reacts at least partially with the first reactant,cyclohexane for example. During the reaction, heat is generated, whichraises the temperature of the first droplets. As the temperature of thefirst droplet rises, evaporation of first liquid or components thereoftakes place, thus lowering the temperature of the droplets. Droplettemperature may be controlled by controlling the rate of evaporation.Control of the rate of evaporation may be conducted by maintainingconstant reactor pressure and by adjusting the rate of condensation ofvapors on the condensing walls of the reaction chamber. This in turn isachieved by adjusting the temperature and rate of heat absorbed by thecondenser in the form of jacket 24. Details of how is this carried outare discussed in a later section with reference to FIG. 6. Although FIG.6 illustrates this for the embodiment of FIG. 5, all condensingmechanisms of this invention may be substantially controlled in themanner described with reference to FIG. 6.

In contrast to the reaction chambers illustrated in FIGS. 1 and 2, theliquid/gas interface is huge in the case of the reaction chambers ofthis invention, and thus, condensation can be an excellent controllingfactor of the rate of evaporation from the first droplets, and in turnan excellent control of the temperature of the first droplets.

The excess gas is removed through gas exit port 38 and valve 39, whilethe first liquid is removed through liquid exit port 40.

The pressure within the reaction chamber is controlled by the flow rateat which the gas enters the reaction chamber 22 through orifices 36 andthe degree of opening of the valve 39, as well as the liquid condensatetemperature.

If the reaction is not complete by the time the first droplets reach thelower end of the reaction chamber, the first liquid may be partly ortotally recirculated from the liquid exit port to the first atomizer 28,as is or after some treatment, well known to the art, to removepartially or substantially totally the reaction product and/or otheradjuncts.

A tremendous difference between the reactors of this invention(illustrated in FIG. 3 for example) and the conventional reactors(illustrated in FIG. 1, for example) is that in the former caserecirculation of liquids, which is very easy, may be required, while inthe latter case, recirculation of gases may be necessary.

Thus, in the case of this invention, the valve 39 may be substantiallyclosed, and second reactant be introduced to the reaction chamber 22 perreaction needs, while merely recirculating the first liquid from theliquid exit port 40 back to the first atomizer 28. In contrast, if thesame is desired for the conventional reactor illustrated in FIG. 1, thegas will have to be recirculated, which is a rather undesirable task.

An additional advantage of the instant invention is that the temperatureof the first droplets, which represent a rather small mass, may becontrolled quickly and easily by internal inside condensation. Incontrast, the big mass of liquid involved in conventional technology isnecessarily very slow regarding forced temperature changes.

In another embodiment of this invention, better illustrated in FIG. 4, acondensation coil 124 is used in lieu of the jacket 25 of FIG. 3. Theoperation of this embodiment regarding internal inside condensation issubstantially the same as described hereinabove for the embodiment ofFIG. 3, with the difference that the internal inside condensation takesplace on the coil 124 instead of the walls of the reaction chamber 122.

In still another highly preferred embodiment of the instant invention,better illustrated in FIG. 5, there is provided a second atomizer 228'in addition to the first atomizer 228. The second atomizer 228' isadapted to form second droplets through nozzles 230' from a secondliquid. The second droplets have a lower temperature than the firstdroplets formed by atomizer 228, and they are used as condensing meansof vapors produced by evaporation of components from the first droplets.

Although the second droplets produced from the second liquid may haveany desired composition, it is preferable that they have at least oneingredient in common with the first droplets produced from the firstliquid. It is more preferable that, if the first droplets comprise afirst set of ingredients and the second droplets comprise a second setof ingredients, the first and second sets comprise the same ingredients.It is even more preferable that the two sets comprise the sameingredients under the same proportions. As a matter of fact, the firstand the second droplets may be parts of the first liquid, which firstliquid has been divided into two streams, a first stream correspondingto the first droplets, and the second stream corresponding to the seconddroplets. The basic difference between the first and the second dropletsis that they are introduced to the reaction chamber at differenttemperatures (higher temperature for the first droplets, and lowertemperature for the second droplets), and maybe different flow rates.The first droplets are utilized to perform the reaction, while thesecond droplets have as a main function to condense vapors produced bythe first droplets, as the reaction proceeds and the temperature of thefirst droplets increases. Mixing of the two types of droplets with eachother is highly undesirable, since it is detrimental to both reactionand condensation.

Therefore, it is very important that as few as possible of the firstdroplets collide with second droplets in their path through the reactionzone. It is believed that the smaller the droplets the less the chancesto collide. Thus, if there is no other compelling reason to increase thesize of the droplets, they should be made to be as small as possible, ofcourse within reason. It is also preferable that regardless of the sizeof the first droplets, the size of the second droplets is maintainedadequately smaller in a manner to reduce the probabilities of collisionbetween first and second droplets.

The operation of this embodiment regarding internal inside condensationis substantially the same as described hereinabove for the embodimentsof FIG. 3 and 4, with the difference that the internal insidecondensation takes place on the second droplets instead of the walls ofthe reaction chamber 22 or the coil 124, respectively.

A controlled reactor device or apparatus 320 of the present inventioncan be exemplified by the schematic diagram illustrated in FIG. 6.Although the internal inside condensation in the example of FIG. 6 isconducted by a set of second droplets, which is highly preferable asdiscussed hereinabove, substantially the same or similar elements andoperation principles may be used, regardless of the type of means usedfor conducting said internal inside condensation.

The controlled reactor device 320 of FIG. 6 comprises a reaction chamber322, which is provided with a first atomizer 328 and a second atomizer328', preferably in the vicinity of the upper end 332 of the reactor322. At the upper end 332, there is also a gas exit port 338 connectedto a valve 339. In the vicinity of the lower end 342, there is provideda gas line 333 ending to one or more orifices 336. A liquid exit port340 is also located in the vicinity of the lower end 342 of the reactionchamber 322.

One or more thermocouples 344, arranged within the reaction zone 334,are connected to a preferably computerized controller 346 through inputlines 344i. The thermocouples 344 may be positioned in any appropriateplaces of the reaction zone 334 in order to monitor the temperature ofthe falling droplets at different distances between the upper end 332and the lower end 442 of the reaction chamber 322, either continuously,or at predetermined intervals of time.

The device 320 is also provided with a source of first liquid, in theform of a tank 348, for example. A first pump 350 is adapted to pump afirst stream of the first liquid from the tank 348 at a first controlledflow rate to a first heat exchanger 352, a first temperature monitor354, a first flow rate monitor or first flow meter 356, and finallythrough first atomizer 328. In the same manner, a second pump 350' isadapted to pump a second stream of the first liquid from the tank 348 ata second controlled flow rate to a second heat exchanger 352', a secondtemperature monitor 354', a second flow rate monitor or second flowmeter 356', and finally through the second atomizer 328'. The heatexchanger may also be a simple heater or a simple cooler or chiller,depending on the reaction to take place and the initial temperature ofthe first liquid from the tank 348. According to the present invention,a heat exchanger may be a conventional heat exchanger, a heater, acooler or a chiller.

The first temperature monitor 354 and the first flow meter 356 areconnected to the computerized controller 346 through input lines 354iand 356i, respectively for providing the computerized controller 346with first temperature and first flow rate information, respectively. Inthe same manner, the second temperature monitor 354' and the second flowmeter 356' are connected to the computerized controller 346 throughinput lines 354i' and 356i', respectively, for providing thecomputerized controller 346 with second temperature and second flow rateinformation, respectively.

There is also provided a gas source 358, which contains the secondreactant, oxygen for example, in the case of oxidation of cyclohexane toadipic acid for example.

The second gas source 358 is connected to a pressurizing pump 360, whichis connected to gas line 333, which in turn leads to the orifices 336 inthe reaction chamber 322. Since the gas in most occasions is alreadypressurized in the gas source, which is usually a suitable tank, thepressurizing pump 360 may be replaced by a valve (not shown) or apressure regulator (not shown), or both.

A pressure gauge 362 is also provided within the reaction chamber 322 inorder to provide pressure information to the computerized controller 346through input line 362'.

Carbon monoxide and carbon dioxide monitors (not shown) are alsopreferably provided to transfer respective information to the controller346 as already discussed earlier.

The preferably computerized controller 346 controls the pumps 350 and350' through output lines 350u and 350u', respectively, and the heatexchangers 352 and 352' through output lines 352u and 352u'respectively. It also controls the valve 339 and the pressurizing pump360 through output lines 339u and 360u, respectively. As alreadymentioned, the pump 360 may be replaced by a valve or pressure regulator(not shown), in which case the valve or pressure regulator arecontrolled through line 360u in place of the pump 360.

In operation of the controlled reaction device, a first stream of thefirst liquid, which comprises for example a mixture of cyclohexane asfirst reactant, a solvent, such as acetic acid for example, a catalyst,such as a cobalt salt for example, an initiator, such as cyclohexanoneor acetaldehyde for example, and other desirable adjuncts, inproportions which may be similar to the ones described in the art forconventional systems, is pumped from tank 348 by pump 350 through theheat exchanger 352, where it assumes a desired temperature, measured bythe temperature monitor 354.

The heated first stream passes through the flow meter 356, where itsflow rate is measured, and then, it enters the reaction chamber throughthe first atomizer 328 and nozzles 330 in the form of atomized orsprayed first droplets at the first atomization temperature as measuredby the temperature monitor 354. Both the first atomization temperatureand the first flow rate are provided to the controller 346 forprocessing. If the temperature provided to the controller 346 is higherthan the desired atomization temperature, the heat exchanger 352i,ordered by the controller 346, through output line 352u, to provide lessheat to the first stream passing through the heat exchanger, until thefirst atomization temperature drops to the desired level. If thetemperature provided to the controller 346 is lower than the desiredatomization temperature, the heat exchanger 352 is ordered by thecontroller 346, through output line 352u, to provide more heat to thefirst stream passing through the heat exchanger 352, until the firstatomization temperature increases to the desired level.

Similarly, if the flow rate as measured by the flow meter 356 andprovided to the controller 346 is higher than the desired first flowrate, the pump 350 is ordered by the controller 346, through output line350u, to lower its pumping action, until the first flow rate drops tothe desired level. If the flow rate as measured by the flow meter 356and provided to the controller 346 is lower than the desired first flowrate, the pump 350 is ordered by the controller 346, through output line350u, to raise its pumping action, until the first flow rate increasesto the desired level.

A second stream of the first liquid, is also pumped from tank 348 bypump 350' through the heat exchanger 352', where it assumes a desiredsecond atomization temperature, lower than the atomization temperatureof the first stream and measured by the temperature monitor 354'.

The heated second stream passes through the flow meter 356', where itsflow rate is measured, and the then, it enters the reaction chamberthrough the second atomizer 328' and nozzles 330' in the form ofatomized or sprayed second droplets at the second atomizationtemperature (lower than the first atomization temperature) as measuredby the temperature monitor 354'. Both the second atomization temperatureand the second flow rate are provided to the controller 346 forprocessing. If the temperature provided to the Controller 346 is higherthan the desired second atomization temperature, the heat exchanger 352'is ordered by the controller 346, through output line 352u', to provideless heat to the second stream passing through the heat exchanger 352',until the second atomization temperature drops to the desired level. Ifthe temperature provided to the controller 346 is lower than the desiredsecond atomization temperature, the heat exchanger 352' is ordered bythe controller 346, through output line 352u', to provide more heat tothe second stream passing through the heat exchanger 352', until thesecond atomization temperature increases to the desired level.

Similarly, if the flow rate as measured by the flow meter 356' andprovided to the controller 346 is higher than the desired second flowrate, the pump 350' is ordered by the controller 346, through outputline 350u', to lower its pumping action, until the second flow ratedrops to the desired level. If the flow rate as measured by the flowmeter 356' and provided to the controller 346 is lower than the desiredsecond flow rate, the pump 350' is ordered by the controller 346,through output line 350u', to raise its pumping action, until the secondflow rate increases to the desired level.

At the same time that the first and second atomizations are takingplace, a gas containing a second reactant, such as oxygen for example,enters the system though gas line 333 and the orifices 336, and moves ina substantially opposite direction than the first and second droplets.The pressure in the reaction chamber 322 is measured by the pressuregauge 362, and the information is fed to the computerized controller 346through input line 362'. If the pressure is higher than a desiredpressure, the controller orders the valve 339 to assume a more openposition, or it orders the pressurizing pump to reduce feeding of gas toline 333, until the pressure assumes the desired value. Since wasteminimization is a very important factor for environmental improvement,the computerized controller is preferably programmed in a manner thatlarger opening of the valve 339 is used as a last resort. If thepressure is lower than the desired one, the controller 346 orders thevalve 339 to assume a more closed position or the pump 360 to pass moregas to line 333 from the gas source 336. The flow of the gas throughline 333 may be measured by a flow meter (not shown) on said line andfed to the computerized controller 346. It becomes then clear that thepressure in the reaction chamber and flow rate of gas to the reactionchamber can be controlled by adjusting the pumping action of thepressurizing pump 360 and the opening of valve 339. As aforementioned,the pressurizing pump 333 may be replaced by other devices, such as apressure regulator for example, if the pressure in the gas source 358 ismaintained at a suitable pressure greater or equal to the desiredpressure in the reaction chamber 322.

In case it is desired to remove inert gases, the opening of valve 339may be increased. Simultaneously, if so desired, second reactant, forexample oxygen, may be forced into the reaction chamber in order tomaintain both the total pressure and the partial pressure of the secondreactant at predetermined levels. A monitor (not shown) for secondreactant may be positioned within the off-gas region to monitor thecontent of second reactant. This information, combined with the knownamounts of second reactant entering the reaction chamber, may be easilycorrelated to the progress of the reaction, by simple mathematicaltechniques well known to the art, and easily performed by thecomputerized controller 346.

As the droplets proceed within the reaction zone 334 from the upper part332 toward the lower end 342 of the reaction chamber 322, the secondreactant, oxygen for example, reacts at least partially with the firstreactant, cyclohexane for example. During the reaction, heat isgenerated, which raises the temperature of the first droplets. As thetemperature of the first droplets rises, evaporation of first liquid orcomponents thereof takes place. As aforementioned, the rate ofevaporation may be controlled by adjusting the rate of condensation ofvapors on the second droplets, the temperature of which is lower. Byincreasing the second flow rate (the flow rate of the second stream) anddecreasing the second atomization temperature, the rate of condensationof vapors on the second droplets increases, resulting in an increase ofvaporization rate from the first droplets, which in turn results incooling of the first droplets. By decreasing the second flow rate (theflow rate of the second stream) and increasing the second atomizationtemperature, the rate of condensation of vapors on the second dropletsdecreases, resulting in an decrease of vaporization rate from the firstdroplets, which in turn results in reduced cooling of the firstdroplets.

It can be seen then that heat transfer from the first droplets to thesecond droplets or any other condensation means is regulated by thecontroller 346. The vapor condensation, of vapors formed from the firstdroplets, on the second droplets may be at least partially controlled byone parameter selected from a group consisting of (a) temperaturedifference between the first and the second atomization temperature, (b)flow rate difference between the first and the second flow rate (c) thevolatiles content of the first liquid, (d) the volatiles content of thesecond liquid, (e) the volatility of the first or second volatiles, and(f) a combination thereof.

It is preferable that the total amount of second reactant allowed toenter the reaction chamber 322 is in the range corresponding to one timestoichiometric to five times stoichiometric, and preferably to two timesstoichiometric, with respect to the total amount of the first reactantfed to the reaction chamber or reaction zone. This is very important forwaste minimization and environmental improvement reasons, since the offgases produced under these conditions are minimized. In one example, ifX moles of first reactant, such as cyclohexane for example, exist in anunreacted state in a reactor to form adipic acid by direct oxidationwith oxygen, then preferably 2.5× to 12.5×, and more preferably 2.5× to5× moles of oxygen are allowed to be present in the reactor, regardlessof whether the reaction is a batch reaction or a continuous reaction.

The thermocouples 344 take the temperature of the droplets and feed thisinformation to the controller 346. In one embodiment of the presentinvention, the controller may order the pump 350' to interrupt pumpingat certain predetermined intervals and for short periods of time. Whenthis occurs, there are no second droplets in the reaction chamber, andtherefore, the thermocouples directly measure the actual temperature ofthe first droplets in substantially the absence of condensation, as thefirst droplets proceed in the reaction zone 334 from the upper end 332to the lower end 342 of the reaction chamber 322. If the interruption ofthe second droplet flow is of sufficiently short duration, the firstdroplets will continue to be cooled by the solvent vaporization effect,and the temperature measured by the controller under these circumstancesrepresents the actual temperature that the first droplets attain due tothe combined effects of heat released by the reaction and solventevaporation, when the rest of the parameters remain constant. If theinterruption is allowed to continue for a sufficiently longer period oftime, then the temperature measured by the controller represents themaximum temperature that the first droplets may attain due to the heatreleased by the reaction, when the rest of the parameters remainconstant. The controller, based on this information, gives appropriateorders to the other components of the device to prevent this temperaturefrom exceeding predetermined limits, if so desired, not only forpurposes of controlling the reaction but also to prevent catastrophicresults in case that the internal condensation is interrupted forprolonged periods of time by accident or otherwise, and the reactionheat released is excessive. This presents an additional safeguard.

Although one thermocouple, preferably close to the lower end 342, may beused for monitoring temperature, it is more preferable to use more thanone thermocouples 344 in the reaction zone 334 for determining the rateof temperature rise, or temperature profile in the droplet path. This isuseful information, since, based on such information, the elevation ofthe second atomizer may be physically lowered to the point where theinternal inside condensation is needed most. Also the controller 346 ispreferably adapted to utilize data concerning temperature profiles inthe reaction chamber in order to regulate the flow rates, atomizationtemperatures of the first and the second liquids, as well as otherparameters as discussed hereinbelow. The higher the temperature changesfrom thermocouple to thermocouple the more drastic the changes orderedby the controller.

Pressure inside the reaction chamber may influence the rates ofevaporation and condensation, and thus it may be used by the controller346, especially in combination with other parameters already discussed,to control the heat exchange between the first and second droplets.Lower pressure causes higher evaporation rate, while higher pressurecauses lower evaporation rate, provided that the vapors are condensed.

The first and second droplets preferably coalesce together into a massof liquid 364, which exits the reactor through liquid exit port 340.Depending on the degree of completion of the reaction, the liquid 364may be re-circulated into the tank 348, preferably after at leastpartial removal of the reaction product, or undergo other treatment,depending on the reaction.

The miscellaneous control parameters according to the preferredembodiments of the instant invention are used in a way that condensationis controlled in a manner that in turn the conversion of the firstreactant in the first droplets, the temperature of the first droplets,and the final composition of the first droplets may be controlled at oneor more predetermined points within the reactor.

There are mainly two aspects to first reactant conversion control. Thefirst is to determine the first reactant conversion as a function of itspath through the reactor, while the second is to control the firstreactant conversion at a desired setpoint or setpoints. The amount ofreaction in the first droplet and the amount of first reactantconversion, as a function of the first droplets path through thereactor, may be calculated by the computerized controller 346--usingmass and energy balances well known to the art--as a function of:

the overall temperature of the combined first and second droplets at acertain point or points within the reactor as determined by one or moreof the thermocouples 344;

first stream inlet flowrate as measured by first flowmeter 356, firstatomization temperature as measured by the first temperature monitor354, and composition as determined to be in tank 348, either because ofmixing known materials in known amounts, or by analytical techniqueswell known to the art, or composition as modified in the first stream byintroduction of desired ingredients through other streams (not shown);

second stream inlet flowrate as measured by second flowmeter 356',second atomization temperature as measured by the second temperaturemonitor 354', and composition as determined to be in tank 348, eitherbecause of mixing known materials in known amounts, or by analyticaltechniques well known to the art, or composition as modified in thesecond stream by introduction of desired ingredients through otherstreams (not shown);

reactor pressure as measured by the pressure gauge 362; and

the concentrations of inert gases, if present, and second reactant, suchas oxygen for example, in the reactor.

The first reactant conversion may also be directly measured by sampleanalysis.

The first reactant conversion may then be controlled by the followingguidelines (implemented alone or in concert by controller 346 and thecorresponding control devices):

conversion can be decreased by decreasing the first atomizationtemperature through the first heat exchanger 352;

conversion can be decreased by decreasing second atomization temperaturethrough the second heat exchanger 352'; this increases condensation onthe second droplets, increasing vaporization from the first dropletsresulting in lowering the temperature of the first droplets, andtherefore, in decreasing conversion;

conversion can be decreased by decreasing catalyst concentration; thiscan be done, for example, by introducing into the first stream a thirdstream (not shown), also controlled by the controller 346, containingall the ingredients of the contents of the tank 348, with lower contentof catalyst or no catalyst; alternatively, in another example, the tank348 can contain substantially all ingredients except catalyst and thethird stream (not shown), also controlled by the controller 346, cancontain substantially only catalyst, preferably dissolved in a liquidmedium, so that controller 346 can change appropriately the flow of thethird stream;

conversion can be decreased by increasing the concentration of the firstreactant in the first liquid; this can be done, for example, byintroducing into the second stream a fourth stream (not shown), alsocontrolled by the controller 346, containing all the ingredients of thecontents of the tank 348, but having higher content of first reactant;alternatively, in another example, the tank 348 can containsubstantially all ingredients except first reactant and the fourthstream (not shown), also controlled by the controller 346, can containsubstantially only first reactant, so that controller 346 can changeappropriately the flow of the fourth stream;

conversion can be decreased by increasing the concentration of volatilesin the first stream; evaporation of volatiles decreases the temperatureresulting in lower conversion; also dilution due to volatilesintroduction leads to lower conversion; incorporation of controlledamounts of volatiles may be achieved by a fifth stream (not shown)entering into the first stream and controlled by the computerizedcontroller 346;

conversion can be decreased by decreasing second reactant concentrationin the reactor; this can be achieved, for example, by introducing intoline 333 an amount of inerts controlled (not shown) by the computerizedcontroller 346; or it can be achieved, in another example, by decreasingthe pumping action of the pressurizing pump 360, or increasing theopening of valve 339, or a combination thereof;

conversion can be decreased by increasing first liquid droplet sizethrough control (not shown) of the first atomizer by the controller 346,using methods well known to the art.

The converse of these guidelines is also true.

It becomes evident then that the desired values of conversion ortransient conversion depend on a number of parameters, and can varybroadly in each particular case. For example, in some occasions, valuesof transient conversion may go as low as 0.05% or even lower. This istrue not only in the context of the present invention, but also in thecontext of our co-pending applications Ser. Nos. 08/477,234, 08/478,257,08/477,195, and 08/475,340, all of which were filed on Jun. 7, 1995.

There are two aspects to first droplet temperature control. The first isto determine the temperature of the first droplet as a function of itspath through the reactor. The second is to control the temperature at adesired setpoint or setpoints.

The first droplet temperature, as a function of its path through thereactor, can be calculated as a function of the following variables:

amount of first reactant conversion having taken place in the firstdroplet as a function of its path through the reactor as calculated bythe computerized controlled 346 or as measured by sample analysis;

first stream inlet flowrate as measured by the first flowmeter 356,first atomization temperature as measured by the first temperaturemonitor 354, the average temperature between the first and seconddroplets as measured by the thermocouples 344, and the composition inthe tank 348, as made or as modified otherwise in the first stream;

second stream inlet flowrate as measured by the second flowmeter 356',second atomization temperature as measured by the second temperaturemonitor 354', the average temperature between the first and seconddroplets as measured by the thermocouples 344, and the composition inthe tank 348, as made or as modified otherwise in the second stream;

reactor pressure as measured by the pressure gauge 362; and

the concentrations of inerts and oxygen in the reactor as computed bythe computerized controller 346, or as measured by direct analysis.

Given this information, the temperature of the first droplet, at a pointor points within the reactor, may be calculated by the computerizedcontroller 346 using mass balances, energy balances, vapor-liquidequilibrium data, and kinetic rate equations for mass and energytransfer well known to the art.

First droplet temperature may then be controlled by the followingguidelines (implemented alone or in concert by the computerizedcontroller 346):

the first droplet temperature can be decreased by decreasing firstatomization temperature as measured by the first temperature monitor354;

the first droplet temperature can be decreased by decreasing secondatomization temperature as measured by the second temperature monitor354;

the first droplet temperature can be decreased by decreasing catalystconcentration; this can be done, for example, by introducing into thefirst stream a third stream (not shown), also controlled by thecontroller 346, containing all the ingredients of the contents of thetank 348, with lower content of catalyst or no catalyst; alternatively,in another example, the tank 348 can contain substantially allingredients except catalyst and the third stream (not shown), alsocontrolled by the controller 346, can contain substantially onlycatalyst, preferably dissolved in a liquid medium, so that controller346 can change appropriately the flow of the third stream;

the first droplet temperature can be decreased by decreasing theconcentration of the first reactant in the first liquid; this can bedone, for example, by introducing into the second stream a fourth (notshown) stream, also controlled by the controller 346, containing all theingredients of the contents of the tank 348, with lower content or nofirst reactant; alternatively, in another example, the tank 348 cancontain substantially all ingredients except first reactant and thefourth stream (not shown), also controlled by the controller 346, cancontain substantially first reactant, so that controller 346 can changeappropriately the flow of the fourth stream;

the first droplet temperature can be decreased by increasing theconcentration of volatiles in the first stream; evaporation of volatilesdecreases the temperature; incorporation of controlled amounts ofvolatiles may be achieved by the fifth stream (not shown) entering intothe first stream and controlled by the computerized controller 346;

the first droplet temperature can be decreased by decreasing secondreactant concentration in the reactor; this can be achieved, forexample, by introducing into line 333 an amount of inerts controlled(not shown) by the computerized controller 346; or it can be achieved,in another example, by decreasing the pumping action of the pressurizingpump 360, or increasing the opening of valve 339, or a combinationthereof;

the first droplet temperature can be decreased by increasing firstliquid droplet size through control (not shown) of the first atomizer bythe controller 346, using methods well known to the art.

The converse of these methods is also true

There are two aspects to first droplet composition control The first isto determine the composition of the first droplet as a function of itspath through the reactor. The second is to control the composition of aselected ingredient, or of a group of selected ingredients whichtogether form a subset of all the ingredients present in the droplet, ata desired value or values.

The first droplet composition, as a function of its path through thereactor, can be calculated as a function of the following variables:

amount of first reactant conversion having taken place in the firstdroplet as a function of its path through the reactor as calculated bythe computerized controlled 346 or as measured by sample analysis;

first stream inlet flowrate as measured by the first flowmeter 356,first atomization temperature as measured by the first temperaturemonitor 354, the average temperature between the first and seconddroplets as measured by the thermocouples 344, and the composition inthe tank 348, as made or as modified otherwise in the first stream;

second stream inlet flowrate as measured by the second flowmeter 356',second atomization temperature as measured by the second temperaturemonitor 354', the average temperature between the first and seconddroplets as measured by the thermocouples 344, and the composition inthe tank 348, as made or as modified otherwise in the second stream;

reactor pressure as measured by the pressure gauge 362; and

the concentrations of inerts and oxygen in the reactor as computed bythe computerized controller 346, or as measured by direct analysis;

temperature of the first droplet as a function of its path through thereactor

Given this information, the composition of the first droplet, at a pointor points within the reactor, may be calculated using mass balances,energy balances, vapor-liquid equilibrium data, and kinetic rateequations for mass and energy transfer well known to the art.

First droplet composition of a selected ingredient, or of a group ofselected ingredients which together form a subset of all the ingredientspresent in the droplet, may be controlled at a desired value or valuesby the following guidelines (implemented alone or in concert):

Content of first reactant can be decreased by increasing firstatomization temperature as described above;

Content of first reactant can be decreased by decreasing secondatomization temperature as described above;

Content of first reactant can be decreased by increasing catalystconcentration as described above;

Content of first reactant can be decreased by decreasing theconcentration of the first reactant in the first liquid, or the firststream or the second stream or a combination thereof, as describedabove;

content of first reactant can be decreased by decreasing theconcentration of volatiles in the first liquid as described above;

content of first reactant can be decreased by increasing second reactantconcentration in the reactor as described above;

content of first reactant can be decreased by decreasing first liquiddroplet size as described above;

content of volatiles can be decreased by increasing first atomizationtemperature as described above;

content of volatiles can be decreased by decreasing second atomizationtemperature as described above;

content of volatiles can be decreased by increasing catalystconcentration in the first stream as described above;

content of volatiles can be decreased by increasing the concentration ofthe first reactant in the first stream as described above;

content of volatiles can be decreased by decreasing the concentration ofvolatiles in the first stream as described above;

content of volatiles can be decreased by increasing second reactantconcentration in the reactor as described above; and ,content ofvolatiles can be decreased by decreasing first droplet size as describedabove.

The converse of these methods is also true.

It should be stressed that when the internal inside condensation isperformed by solid surfaces within the reaction chamber, and not bymeans of second droplets, the first droplet temperature can be directlymeasured by thermocouples positioned in desired locations of thereaction chamber.

The use of second droplets, however, for condensation is of utmostimportance, since it presents an unprecedented way of ultra-efficientmanner to control condensation within the reaction zone, in anexothermic reaction.

The second liquid may have the same composition as the first liquid, asdescribed above where it is in the form of a second stream of the firstliquid, or it may have a different composition. It is highly preferablethat it has the same composition. It may also have such a composition sothat the mass of the liquid 364 after at least partial removal of thereaction product assumes a composition similar to the composition of thefirst liquid. For example, in the case of oxidation of cyclohexane toadipic acid, the second liquid may contain an excess of cyclohexane,which will virtually replace in liquid mass 364 the cyclohexane whichwill react in the first liquid. Absence of catalyst in the second liquidpromotes absence of reaction in the second droplets. The second liquidmay also be immiscible with the first liquid, so that they may beseparated easily after removal from the reaction chamber. Nevertheless,close similarity of the first and second liquids, highly simplifies theprocess, and as aforementioned, it is highly preferable.

In a different embodiment of the present invention, better shown in FIG.7, the reactor 422 comprises a first atomizer 428, and a ring 428',which is adapted to distribute the second liquid substantially uniformlyon the inside surface of the reactor 422 in the form of a thick film orcurtain 466. The second liquid has a lower temperature than the firstliquid, and condensation of vapors produced by the first droplets takesplace on the curtain of said second liquid which covers the periphery ofthe reaction zone.

The operation of this embodiment is substantially the same as theoperation of the previous embodiments, with the difference that thevapors produced by the first droplets condense on the curtain or thickfilm 446.

In still a different embodiment of the present invention, better shownin FIG. 8, the reactor 522 comprises a first atomizer 528, and a ring528', which is adapted to distribute the second liquid substantiallyuniformly on the inside surface of the reactor 522 in the form of athick film or curtain 566, as in the case of the previous embodiment.The second liquid has a lower temperature than the first liquid, andcondensation of vapors produced by the first droplets takes place on thecurtain of said second liquid which covers the periphery of the reactionzone. At the lower end 542 of the reactor 522 there is provided a pan568, ending to a pan exit 570, while the reaction chamber 522 ends to areactor exit 572.

The operation of this embodiment is substantially the same as theoperation of the previous embodiment, with the difference that most ofthe reacted material falls into the pan and removed from the pan exit570, while most of the condensed material is removed from the reactorexit 572. This at least partial separation of reacted material fromcondensed material is important, especially when the composition of thecurtain 566 differs substantially from the composition of the firstliquid.

In still a different embodiment, better shown in FIG. 9, there isprovided a jacket 624, similar to the jacket 24 of the embodimentdepicted in FIG. 3. The jacket 624 provides a cold solid surface in thereactor 622, on which surface vapors are condensed and are removedthrough the reactor exit 672, while most of the reacted material isremoved from the fan exit 670 after being collected by pan 668.

The operation of this embodiment is substantially the same as theoperation of the immediately previous embodiment.

As aforementioned, the methods and the devices of the instant inventionmay be used for substantially any types of exothermic reactions, whereina first reactant in a liquid reacts with a second reactant in a gas toform a reaction product. Such reactions include, but are not limited toesterifications, ether formations, amide or imide formations, saltformations, ammoniations, nitrations, oxidations, and the like.Oxidations are particularly suitable for oxidation reactions of organiccompounds, wherein the major portion of the reaction product is anoxidation product different than CO, CO₂, or a mixture thereof. One ofthe reasons why this is so, is that, due to the intricate criticalitiesof the present invention, the reaction rates, reaction homogeneity,yield, and other important properties are considerably improved, whilein the absence of said criticalities complete oxidation to CO/CO₂ wouldtake place. Actually, the same conditions of atomization without saidcriticalities, are presently used in combustion engines of automobilesand other devices, to substantially completely oxidize (combust or burnin other words) organic compounds such as gasoline to a mixture ofCO/CO₂.

In contrast, according to the present invention, if for example, thefirst reactant is cyclohexane, the major portion of the oxidationproduct may be substantially cyclohexanol, cyclohexanone,cyclohexylhydroperoxide, caprolactone, adipic acid, the like, andmixtures thereof. Organic acids are preferable oxidation products.

Many catalysts used for reactions, such as oxidations for example, aretransition metals having more than one valence states. Their majorcatalytic action is exhibited when they are at a higher valance statethan their lowest valance state at which they exist as ions. One goodexample is cobalt in the case of oxidation of cyclohexane to adipicacid. An initiation period before the oxidation starts has often beenattributed by researches to the addition of cobalt ions at a valancestate of II. The cobalt catalyst is added at valance state II becausecobaltous acetate, for example, is more readily available and it is lessexpensive than cobaltic acetate. Thus, it takes a period of time for thecobaltous ion to be oxidized to cobaltic ion and start acting as acatalyst according to methods in the art so far, unless cobalt II isused, or the cobalt II is preoxidized. Even then, it takes time tooxidize cobalt II to cobalt III ions, due to the small interfaceprovided by bubbling the gas through the solution.

In the case of the instant invention, this period of oxidation becomesconsiderably smaller because of the high interfacial surface areaprovided relative to liquid mass in the reaction chamber as atomizedfirst droplets. In addition, the cobaltous ion can be pre-oxidized.

As aforementioned, reactions, such as oxidations for example, accordingto this invention, are non-destructive oxidations, wherein the oxidationproduct is different than carbon monoxide, carbon dioxide, and a mixturethereof. Of course, small amounts of these compounds may be formed alongwith the oxidation product, which may be one product or a mixture ofproducts.

Examples include, but of course, are not limited to preparation of C₅-C₈ aliphatic dibasic acids from the

corresponding saturated cycloaliphatic hydrocarbons, such as for examplepreparation of adipic acid from cyclohexane;

preparation of C₅ -C₈ aliphatic dibasic acids from the correspondingketones, alcohols, and hydroperoxides of saturated cycloaliphatichydrocarbons, such as for example preparation of adipic acid fromcyclohexanone, cyclohexanol, and cyclohexylhydroperoxide;

preparation of C₅ -C₈ cyclic ketones, alcohols, and hydroperoxides fromthe corresponding saturated cycloaliphatic hydrocarbons, such as forexample preparation of cyclohexanone, cyclohexanol, andcyclohexylhydroperoxide from cyclohexane; and

preparation of aromatic multi-acids from the corresponding multi-alkylaromatic compounds, such as for example preparation of phthalic acid,isophthalic acid, and terephthalic acid from o-xylene, m-xylene andp-xylene, respectively.

Regarding adipic acid, the preparation of which is especially suited tothe methods and devices or apparatuses of this invention, generalinformation may be found in a plethora of U.S. Patents, among otherreferences. These, include, but are not limited to:

U.S. Pat. Nos. 2,223,493; 2,589,648; 2,285,914; 3,231,608; 3,234,271;3,361,806; 3,390,174; 3,530,185; 3,649,685; 3,657,334; 3,957,876;3,987,100; 4,032,569; 4,105,856; 4,158,739 (glutaric acid); 4,263,453;4,331,608; 4,606,863; 4,902,827; 5,221,800; 5,321,157; and 5,463,119.

Diacids (for example adipic acid, phthalic acid, isophthalic acid,terephthalic acid, and the like) or other suitable compounds may bereacted, according to well known to the art techniques, with a thirdreactant selected from a group consisting of a polyol, a polyamine, anda polyamide in a manner to form a polymer of a polyester, or apolyamide, or a (polyimide and/or poyamideimide), respectively.Preferably the polyol, the polyamine, and the polyamide are mainly adiol, a diamine, and a diamide, respectively, in order to avoidexcessive cross-linking. The polymer resulting from this reaction may bespun by well known to the art techniques to form fibers.

Examples demonstrating the operation of the instant invention have beengiven for illustration purposes only, and should not be construed aslimiting the scope of this invention in any way. Although this inventionhas been mainly exemplified with oxidation process, any exothermicreaction between a liquid and a gas (under the conditions of thereaction) is includes in the realm of the instant invention. In additionit should be stressed that the preferred embodiments discussed in detailhereinabove, as well as any other embodiments encompassed within thelimits of the instant invention, may be practiced individually, or inany combination thereof, according to common sense and/or expertopinion. Individual sections of the embodiments may also be practicedindividually or in combination with other individual sections ofembodiments or embodiments in their totality, according to the presentinvention. These combinations also lie within the realm of the presentinvention. Furthermore, any attempted explanations in the discussion areonly speculative and are not intended to narrow the limits of thisinvention.

In the different figures of the drawing, numerals differing by 100represent elements which are either substantially the same or performthe same function. Therefore, in the case that one element has beendefined once in a certain embodiment, its re-definition in otherembodiments illustrated in the figures by the same numerals or numeralsdiffering by 100 is not necessary, and it has been often omitted in theabove description for purposes of brevity.

The words "inlet line" and "outlet line" are used to signify linesadapted to transfer materials for the operation of the process, such asvolatiles, reaction products, off-gases, and the like, for example. Thewords "input line" and "output line" have been used to signify linesadapted to transmit signals, which are mostly electrical, but they canalso be hydraulic, pneumatic, optical, acoustic, and the like, forexample.

A diagonal arrow through an element denotes that the element iscontrolled though a line, preferably electrical, connected to the arrow.

Internal condensation according to this invention is condensation ofcondensibles, which takes place within the pressurized system and beforepressure drop to about atmospheric pressure. Inside condensation orinside internal condensation is condensation which takes place withinthe reaction chamber.

Condensibles are substances having a boiling point higher than 15° C.,while non condensibles are substances that have a boiling point of 15°C. and lower. It should be understood that when referring tocondensibles, it is meant "mostly condensibles" and when referring tonon-condensibles it is meant "mostly non-condensibles", since smallamounts of one kind will be mixed with the other kind at substantiallyall times.

In cases where dilution or concentration of the droplets occurs as theytravel from the atomizer to the sample collector, such dilution has tobe taken into account in the calculation performed by the computerizedcontroller by monitoring the sources of dilution or concentration andusing well known to the art techniques.

Response time between changing one variable or parameter and the resultit brings about should also be taken into account, and the controllershould be calibrated or programmed accordingly, by well known to the arttechniques.

What is claimed is:
 1. A method of forming a polymer wherein a reactionproduct different than carbon monoxide or carbon dioxide is made in areaction zone by reacting a first reactant contained in a first liquidwith a second reactant contained in a gas, the first reactant and thesecond reactant characterized by an ability to react with each other inan exothermic manner, the method comprising the steps of:atomizing thefirst liquid to form a plurality of first droplets having an averagedroplet size in the gas at a first flow rate, at a first atomizationtemperature, and at a reaction pressure; reacting at least partially thefirst reactant with the second reactant to form the reaction product andrelease heat; evaporating at least part of the first liquid, therebyremoving at least a portion of the released heat; and restricting theportion of removed heat within predetermined limits by causingcontrolled condensation within the reaction zone; wherein the firstreactant comprises a compound selected from a group consisting ofcyclohexane, cyclohexanone, cyclohexanol, cyclohexylhydroperoxide,o-xylene, p-xylene, m-xylene, a mixture of at least two of cyclohexane,cyclohexanone, cyclohexanol, and cyclohexylhydroperoxide, and a mixtureof at least two of o-xylene, p-xylene, and m-xylene; the second reactantcomprises oxygen; the reaction product comprises a compound selectedfrom a group consisting of adipic acid, phthalic acid, isophthalic acid,and terephthalic acid; and the method further comprises a step ofreacting said reaction product with a third reactant selected from agroup consisting of a polyol, a polyamine, and a polyamide in a mannerto form a polymer of a polyester, or a polyamide, or a (polyimide and/orpolyamideimide), respectively.
 2. A method as defined in claim 1,wherein the controlled condensation is caused by a second liquidatomized in the form of second droplets having a second average dropletsize within the reaction zone.
 3. A method as defined in claim 2,wherein the second liquid contains volatiles at a desired content and adesired volatility, and enters the reaction zone under a conditionselected from a group consisting of a second flow rate, a secondatomization temperature, and a combination thereof, the secondatomization temperature being lower than the first atomizationtemperature.
 4. A method as defined in claim 3, wherein the first liquidcontains volatiles at a desired content and a desired volatility, andwherein the condensation is at least partially controlled by oneparameter selected from a group consisting of (a) temperature differencebetween the first and the second atomization temperature, (b) flow ratedifference between the first and the second flow rate (c) the volatilescontent of the first liquid, (d) the volatiles content of the secondliquid, (e) the volatility of the first or second volatiles, and (f) acombination thereof.
 5. A method as defined in claim 1, wherein thecondensation is controlled by changing the reaction pressure.
 6. Amethod as defined in claim 2, wherein the first liquid comprises a firstset of ingredients, and the second liquid comprises a second set ofingredients, the first set and the second set having at least one commoningredient.
 7. A method as defined in claim 6, wherein the first set andthe second set comprise substantially the same ingredients.
 8. A methodas defined in claim 6, wherein the first set and the second set comprisesubstantially the same ingredients, substantially under the sameproportions.
 9. A method as defined in claim 6, wherein the first setand the second set consist of substantially the same ingredients,substantially under the same proportions.
 10. A method as defined inclaim 4, wherein the first liquid comprises a first set of ingredients,and the second liquid comprises a second set of ingredients, the firstset and the second set having at least one common ingredient.
 11. Amethod as defined in claim 10, wherein the first set and the second setcomprise substantially the same ingredients.
 12. A method as defined inclaim 10, wherein the first set and the second set consist ofsubstantially the same ingredients, substantially under the sameproportions.
 13. A method as defined in claim 1, wherein the controlledcondensation is caused by a solid surface within the reaction zone. 14.A method as defined in claim 1, wherein the controlled condensation iscaused by a solid surface in the periphery of the reaction zone.
 15. Amethod as defined in claim 14, further comprising a step of at leastpartially separating condensed material from reacted material.
 16. Amethod as defined in claim 1, wherein the controlled condensation iscaused by a liquid surface in the periphery of the reaction zone.
 17. Amethod as defined in claim 16, further comprising a step of at leastpartially separating condensed material from reacted material.
 18. Amethod of forming a polymer wherein a reaction product different thancarbon monoxide or carbon dioxide is made by reacting a first reactantcontained in a first liquid with a second reactant contained in a gas,the first reactant and the second reactant characterized by an abilityto react with each other in an exothermic manner, the method comprisingthe steps of:dividing the first liquid into a first stream and to asecond stream; causing the first stream to have a first atomizationtemperature and the second stream to have a second atomizationtemperature lower than the first atomization temperature; atomizing thefirst stream to form a plurality of first droplets in the gas at a firstflow rate and at the first atomization temperature; atomizing the secondstream to form a plurality of second droplets in the gas at a secondflow rate and at the second atomization temperature; reacting at leastpartially the first reactant in the first droplets with the secondreactant to form the reaction product and release heat; and maintainingfirst droplet temperature within predetermined limits by evaporation ofat least part of the first liquid from the first droplets, andcondensation of at least part of the evaporated first liquid on thesecond droplets; wherein the first reactant comprises a compoundselected from a group consisting of cyclohexane, cyclohexanone,cyclohexanol, cyclohexylhydroperoxide, o-xylene, p-xylene, in-xylene, amixture of at least two of cyclohexane, cyclohexanone, cyclohexanol, andcyclohexylhydroperoxide, and a mixture of at least two of o-xylene,p-xylene, and m-xylene; the second reactant comprises oxygen; thereaction product comprises a compound selected from a group consistingof adipic acid, phthalic acid isophthalic acid and terephthalic acid,and the method further comprises a step of reacting said reactionproduct with a third reactant selected from a group consisting, of apolyol, a polyamine, and a polyamide in a manner to form a polymer of apolyester, or a polyamide, or -l (polyimide and/or polyamideimide),respectively.
 19. A method as defined in claim 18, wherein thecondensation is at least partially controlled by one parameter selectedfrom a group consisting of (a) temperature difference between the firstand the second atomization temperature, (b) flow rate difference betweenthe first and the second flow rate (c) the volatiles content of thefirst liquid, (d) the volatiles content of the second liquid, (e) thevolatility of the first or second volatiles, and (f) a combinationthereof.
 20. A method of forming a polymer wherein a reaction productdifferent than carbon monoxide or carbon dioxide is made by reacting afirst reactant contained in a first liquid with a second reactantcontained in a gas, the first reactant and the second reactantcharacterized by an ability to react with each other in an exothermicmanner, the method comprising the steps of:dividing the first liquidinto a first stream and to a second stream; causing the first stream tohave a first atomization temperature and the second stream to have asecond atomization temperature lower than the first atomizationtemperature; atomizing the first stream to form a plurality of firstdroplets in the gas at a first flow rate and at the first atomizationtemperature; atomizing the second stream to form a plurality of seconddroplets in the gas at a second flow rate and at the second atomizationtemperature; reacting at least partially the first reactant in the firstdroplets with the second reactant to form the reaction product andrelease heat; and maintaining first droplet temperature withinpredetermined limits by transferring heat from the first droplets to thesecond droplets; wherein the first reactant comprises a compoundselected from a group consisting of cyclohexane, cyclohexanone,cyclohexanol, cyclohexylhydroperoxide, o-xylene, p-xylene, m-xylene, amixture of at least two of cyclohexane, cyclohexanone, cyclohexanol, andcyclohexylhydroperoxide, and a mixture of at least two of o-xylenep-xylene, and m-xylene, the second reactant comprises oxygen; thereaction product comprises a compound selected from a group consistingof adipic acid, phthalic acid, isophthalic acid, and terephthalic acid;and the method further comprises a step of reacting said reactionproduct with a third reactant selected from a group consisting of apolyol, a polyamine, and a polyamide in a manner to form a polymer of apolyester, or a polyamide, or a (polyimide and/or polyamideimide),respectively.
 21. A method as defined in claim 20 wherein the heattransfer comprises a step of controlling condensation on the seconddroplets, which condensation is at least partially controlled by oneparameter selected from a group consisting of (a) temperature differencebetween the first and the second atomization temperature, (b) flow ratedifference between the first and the second flow rate (c) the volatilescontent of the first liquid, (d) the volatiles content of the secondliquid, (e) the volatility of the first or second volatiles, and (f) acombination thereof.
 22. A method as defined in claim 1, wherein a totalamount of second reactant is fed to the reaction zone, the total amountof second reactant being in a range corresponding to one timestoichiometric to two times stoichiometric with respect to a totalamount of first reactant fed to the reaction zone.
 23. A method asdefined in claim 2, wherein a total amount of second reactant is fed tothe reaction zone, the total amount of second reactant being in a rangecorresponding to one time stoichiometric to two times stoichiometricwith respect to a total amount of first reactant fed to the reactionzone.
 24. A method as defined in claim 4, wherein a total amount ofsecond reactant is fed to the reaction zone, the total amount of secondreactant being in a range corresponding to one time stoichiometric totwo times stoichiometric with respect to a total amount of firstreactant fed to the reaction zone.
 25. A method as defined in claim 13,wherein a total amount of second reactant is fed to the reaction zone,the total amount of second reactant being in a range corresponding toone time stoichiometric to two times stoichiometric with respect to atotal amount of first reactant fed to the reaction zone.
 26. A method asdefined in claim 18, wherein a total amount of second reactant is fed tothe reaction zone, the total amount of second reactant being in a rangecorresponding to one time stoichiometric to two times stoichiometricwith respect to a total amount of first reactant fed to the reactionzone.
 27. A method as defined in claim 20, wherein a total amount ofsecond reactant is fed to the reaction zone, the total amount of secondreactant being in a range corresponding to one time stoichiometric totwo times stoichiometric with respect to a total amount of firstreactant fed to the reaction zone.
 28. A method as defined in claim 1further comprising a step of spinning the polymer into fibers.
 29. Amethod as defined in claim 4, further comprising a step of spinning thepolymer into fibers.
 30. A method as defined in claim 18, furthercomprising a step of spinning the polymer into fibers.
 31. A method asdefined in claim 20, further comprising a step of spinning the polymerinto fibers.
 32. A method as defined in claim 4, wherein the firstliquid contains a catalyst at a desired concentration, the first andsecond reactants are characterized by desired concentrations, theexothermic reaction is characterized by a conversion of the firstreactant to reaction product, the exothermic reaction takes place in areaction zone the first droplets have a path within said reaction zonesaid first droplets have a temperature as function of their path throughthe reaction zone, wherein the second droplets have also a path throughthe reaction zone, and wherein said conversion is controlled by aparameter selected from a group consisting of:changing the firstatomization temperature; changing the second atomization temperature;changing the catalyst concentration; changing the first reactantconcentration in the first liquid; changing the volatiles content in thefirst liquid; changing the volatiles content in the second liquid;changing the second reactant concentration; changing the average dropletsize of the first liquid; and a combination thereof; and wherein saidfirst droplet temperature is controlled by a parameter selected from agroup consisting of: changing the first atomization temperature;changing the second atomization temperature; changing the catalystconcentration, changing the first reactant concentration; changing thevolatiles content in the first liquid; changing the volatiles content inthe second liquid; changing the second reactant concentration: changingthe average droplet size of the first liquid; and a combination thereof.33. A method as defined in claim 2, wherein the average droplet size ofthe second liquid is maintained at least adequately smaller than theaverage droplet size of the first liquid in a manner to decrease theprobabilities of first droplets to collide with second droplets ascompared to such probabilities when the average size of the seconddroplets is substantially the same as the average size of the firstdroplets.
 34. A method as defined in claim 4, wherein the averagedroplet size of the second liquid is maintained at least adequatelysmaller than the average droplet size of the first liquid in a manner todecrease the probabilities of first droplets to collide with seconddroplets as compared to such probabilities when the average size of thesecond droplets is substantially the same as the average size of thefirst droplets.